IMO C

IMO E
they and their can refer to 'products' or traits
and i have seen use of because of .....as well
so E looks good to me.

Paleontologist Stephen Jay Gould has argued that many biological traits are not the products of natural selection, favored due to their enhancement of reproduction or survival, but that they are simply random by-products of other evolutionary developments.

(A) due to their enhancement of reproduction or survival, but that they are

(B) due to the reproduction or survival they enhance, but they are

(C) because they enhance reproduction or survival, but

(D) because they enhance reproduction or survival, but are

(E) because of enhancing reproduction or survival, but are

The issues:

See the following sentences:

They are not players in the national team but are actors in the national film club.

Lessons:

1. No COMMA in case of list of Two things.
2. One subject has two verbs; therefore, no comma between the verbs are used.

--> The same rule is tested in this sentence.

The above sentence can be re-written as follows:

They are not players in the national team, because they did not qualify in the fitness test, but are actors in the national team.

Mind it:

see the blue portion of the sentence. This blue portion is just non-essential modifier, which has been set off by commas. Such type of modifier can be eliminated without losing the grammatical accuracy of the sentence.

Now, come to the sentence:

Paleontologist Stephen Jay Gould has argued that many biological traits are not the products of natural selection, favored due to their enhancement of reproduction or survival, but that they are simply random by-products of other evolutionary developments.

==> IF we eliminate the non-essential part of the sentence we get the skeleton as follows:

Biological traits are not the products of natural selection but that they are simply random by-products of other evolutionary developments.

Now analyze this very basic part of the sentence as follows:

1. One subject, traits, has two verbs--are and are.
2. We need not repeat the subject if the subject is same for the two verbs, but the the original sentence has repeat the subject. Now, have one thing in mind that all the options that have repeated the subject are wrong.

---> This kills A and B.

3. The following two expressions are correct:

---> He is not an X but a Y.
---> He is not an X but is a Y.

Now, there is a question in your mind. When do we need to use "but y" and when to use "but is Y".

Answer:

If the use of only "but y" makes the sentence ambiguous, then use "but is Y".

Example:

They are not the players in the national team, because they did not pass in the test for players, but actors in the national film club.

---> Look at the last part of the sentence "for player, but actors". This may be misread by first reading.
One may think that "they did not pass in the test for players but they passed in the test for actors"

So, in this case the use of "but Y" is ambiguous.

==> This kills C.

Noe, come to the modifier portion:

We know the following:

1. Because + clause
2. Because of + NOUN

"because of enhancing reproduction or survival" is NOT grammatically wrong, but it has problem in meaning. Who enhance? we are not sure. So, the use of "they enhance" is fine because "they" clearly refers to "traits".

==> This kills E.

Answer is D.

IMO A.

Parallelism.
argued (1) that many biological traits are.....but (2) that they are....

gmat_perfect wrote:

(D) because they enhance reproduction or survival, but are

Answer is D.

In that case,

because products enhance reproduction or survival, but are

because traits enhance reproduction or survival, but are

It can give either meaning i guess.

I would go with C.

replace due to with caused by. Doesn't make sense in the given sentence. Rule out A and B.

E does not spell out clearly that the biological traits that are products of natural selection enhance reproduction or survival. Rule out E.

Between C and D.

C - Biological traits are not A but B.
D - Biological traits are not A but are B.

I think C is a better construction.

gmat_perfect wrote:
If the use of only "but y" makes the sentence ambiguous, then use "but is Y".

Example:

They are not the players in the national team, because they did not pass in the test for players, but actors in the national film club.

---> Look at the last part of the sentence "for player, but actors". This may be misread by first reading.
One may think that "they did not pass in the test for players but they passed in the test for actors"

Don't agree at all.

This meaning can be construed only if we have a for before actors. Without for, the fragment does not pass the parallelism test and thus coming to the conclusion that "they did not pass in the test for players but they passed in the test for actors" is faulty.

Unless I am not that clear on my knowledge of this topic, I would pick C. The answer jumps out at me for several reasons. First, we aren't going to be using due to in this sentence because that word means caused by and because of means as a result of. Eliminate A and B. E is clearly out because it is not the correct way of wording a sentence (because of enhancing...but are..). I feel as if C is 100% the correct answer because it uses the correct wording (because of) and uses but and not but are. But, in this case, is correct because it simply is the way you should say this sentence. Maybe I make this assertion because I am a native speaker, but I feel as if there is no denying C. Fairly easy question in my opinion.

i`d go with C
clearly A and B are out.
i guest they test idiom here: not X, but Y
so, for me it sounds: are not products......., but .... by-products,
it seems to me that with second are after but, the sentence must looks like:not are products , but are by-products and it is not our case
so we don`t need second are, after but,D and E are out
left with C
waiting for oa?

frank1 wrote:

gmat_perfect wrote:

(D) because they enhance reproduction or survival, but are

Answer is D.

In that case,

because products enhance reproduction or survival, but are

because traits enhance reproduction or survival, but are

It can give either meaning i guess.

Nope, for two very strong reasons "they" cannot refer to ''products":

1. Both "they" and "traits" are the subjects of their clause--meaning they are parallel.
2. Products cannot enhance reproduction or survival.

niksworth wrote:I would go with C.

replace due to with caused by. Doesn't make sense in the given sentence. Rule out A and B.

E does not spell out clearly that the biological traits that are products of natural selection enhance reproduction or survival. Rule out E.

Between C and D.

C - Biological traits are not A but B.
D - Biological traits are not A but are B.

I think C is a better construction.

gmat_perfect wrote:
If the use of only "but y" makes the sentence ambiguous, then use "but is Y".

Example:

They are not the players in the national team, because they did not pass in the test for players, but actors in the national film club.

---> Look at the last part of the sentence "for player, but actors". This may be misread by first reading.
One may think that "they did not pass in the test for players but they passed in the test for actors"

Don't agree at all.

This meaning can be construed only if we have a for before actors. Without for, the fragment does not pass the parallelism test and thus coming to the conclusion that "they did not pass in the test for players but they passed in the test for actors" is faulty.

Yes, the red part is faulty because two clauses have been joined by AND only. We need to use COMMA+FANBOYS.

Okay.
Let me refine the sentence.

They have not applied for the position of players, because they are not eligible for the position of players, but for the position of actors in the national film club.

--> now read the sentence.

I think it will change your thought.

I think the OA for this one is D.

If the OA were not D, the option D would be written in other manner. I have seen some sentences in GMATPREP where such type of tricks have been used.

Example:

1. COMMA + VERBING has been used to modify NOUN in a sentence.

The Chicago and Calumet Rivers originally flowed into the St. Lawrence by way of Lake Michigan, but having been redirected by constructing canals so that the water now empties into the Mississippi by way of the Illinois River.

(A) Rivers originally flowed into the St. Lawrence by way of Lake Michigan, but having been redirected by constructing
(B) Rivers had originally flowed into the St. Lawrence by way of Lake Michigan, but they have been redirected by constructing
(C) Rivers, which originally flowed into the St. Lawrence by way of Lake Michigan but have been redirected by the construction of
(D) Rivers, originally flowing into the St. Lawrence by way of Lake Michigan, but having been redirected by the construction of
(E) Rivers, originally flowing into the St. Lawrence by way of Lake Michigan, have been redirected through the construction of

2. Usually we know "cite X as Y" is correct, but in the following sentence the idiom has been changed into "cite as Y X". Here, X has been modified by some words, which makes the sentence convoluted to read in the natural way as "cite X as Y".


The 151 member governments of the World Bank are expected to increase the bank's funding by $75 billion, though some United States legislators cite an obstacle to congressional passage being the concern that the bank's loans will help foreign producers compete with American businesses.

(A) an obstacle to congressional passage being the concern
(B) a concern as an obstacle to congressional passage
(C) as an obstacle to congressional passage the concern
(D) the concern, an obstacle to congressional passage,
(E) as an obstacle for Congress to pass it the concern

I am working on it. I will let you know more on this issue.

Thanks for raising question on this; otherwise, I would not search for it.

Paleontologist Stephen Jay Gould has argued that many biological traits are not the products of natural selection, favored due to their enhancement of reproduction or survival, but that they are simply random by-products of other evolutionary developments.

A due to their enhancement of reproduction or survival, but that they are
B due to the reproduction or survival they enhance, but they are
C because they enhance reproduction or survival, but
D because they enhance reproduction or survival, but are
E because of enhancing reproduction or survival, but are

Quickest approach:

The correct idioms are either are not X but Y or are not X but are Y. Eliminate A and B.

In E, because of enhancing (because of + gerund) is not idiomatic. Eliminate E.

The only difference between C and D is the inclusion of are in D. In leaving out are, answer choice C becomes ambiguous; it is not crystal clear what thought is being completed by the word but. The sentence could be saying:

...favored...but simply random...

or

...not the products of natural selection...but simply random by-products...

Answer choice D makes the meaning crystal clear:

...are not the products of natural selection...but are simply random by-products...

Eliminate C. The correct answer is D.

@gmat_perfect :

If the OA were not D, the option D would be written in other manner. I have seen some sentences in GMATPREP where such type of tricks have been used.

What do you mean by above statement especially D would have been written in different manner ? I had thought C as the correct answer earlier.

Thanks GMATGuru.

OA is D.
Thanks Guys!! [/spoiler]

@GMATGURUNY :

The correct idioms are either are not X but Y or are not X but are Y. Eliminate A and B.

Q1> I ignore for the moment that due to is incorrect here . Can we really eliminate A and B for those reasons ? WHy ?

"But that they are" and but they are" simple take subject of the previous clause and ,in my opinion, can we written this way .

Q2 > I would like to know the usage of "that" in "But that they are" ? Why ? I understand that parallelism requires "that " to be used if second clause is independent (I said that clause1 and that clause2), but , if second clause is treated as independent, an it take the subject of the first clase as is the case here ? in "but that they are " and in "but they are" both "they" reer to the subject of the previous clasue.