A semicolon is used to separate two independent clause.So,if you are reading the two clauses each individually should be complete and make correct sense.

Correct:
Ex: I walked to school,I later ate my lunch.

Incorrect:
Andrew and Lisa are inseparable;doing everything together.


(This is from Manhattan Guide)

I do agree semicolon can be used to eliminate but is there any other flaw in the sentence

IMO - there are a couple of problems with E.

...'appear equal in size when they are seen on a branch or in a nest'... Lacks clarity. Option C provides some of it by saying '....when sitting on a branch ....'.

Second, Option E does not clearly separate the second clause as does Option C.

Given that this does not seem to the OA, can someone point the error in my approach ? Also, an explanation of the approach/errors for the question.

Here is the question with the dashes and commas in place so that you can navigate a little easier.

"While the Eastern Whip-poor-will-a nocturnal bird that feeds mostly in the very early morning-and the Common Nighthawk-a nocturnal bird from the same family that, despite its name, feeds mostly during the morning and evening-appear equal in size to each other when sitting on a branch or in a nest, in the air, the Common Nighthawk appears much larger due to its greater wingspan."

A. appear equal in size to each other when sitting on a branch or in a nest, in the air, the Common Nighthawk appears much larger due to its greater wingspan.

B. appear equal in size to one another when sitting on a branch or in a nest, in the air, the Common Nighthawk appears much larger due to its greater wingspan.

C.appear equal in size when sitting on a branch or in a nest; in the air, the Common Nighthawk appears much larger because of its greater wingspan.

D.appear equal in size to each other when they are sitting on a branch or in a nest, in the air, the Common Nighthawk appears much larger because of its greater wingspan

E.appear equal in size when they are seen on a branch or in a nest, in the air, the Common Nighthawk appears much larger because of its greater wingspan.



As you can see this makes it much easier to basically skip over entire modifiers and basically have a sentence that says "While the Eastern Whip-poor-will...and the Common Nighthawk...appear equal in size to each other when sitting on a branch or in a nest, in the air, the Common Nighthawk appears much larger due to its greater wingspan.

Here is the explanation from the Veritas Free Question Bank. https://www.veritasprep.com/gmat-question-bank/

"Explanation: The first thing to do on this problem is to get rid of all the garbage by using the slash and burn technique. The sentence starts with lots of unnecessary information and should be read like this: "While the two birds appear..." After simplifying that, the easiest answer to eliminate is (C). You cannot start a sentence with "While the two birds appear..." and then have a semicolon. When a semi-colon is used in a sentence like this, each portion on either side of the semi-colon must be a stand-alone sentence.

In (A), (B), and (D) there appears to be a choice between "each other" and "one another" but that is a false decision point. "Each other" is used when there are two distinct entities or groups and "one another" is used when there are multiple entities or groups. It is unclear and unimportant in this sentence whether many birds are being referred to or each group of birds distinctly.

The big problem in (A), (B) and (D) is the meaning: in those three sentences, the language infers that the birds only look this way to each other/one another when they are in certain situations. From the end of the sentence, it is clear that the goal of the sentence is to show the difference in how they look to anyone/anything when they are sitting on a branch or a nest vs. in the air.

Also, in (A) and (B) "due to" is incorrect: when you are answering the question why, you should use "because" or a proper synonym. "Due to" means attributable to and can only be used with a linking verb: for instance, "x is "due to" y". Correct answer is (E). The birds appear equal in size when they are seen (not when they are looking at each other/ one another) by anyone and in the air one appears larger "because" of its wingspan."

GMAT 2805 - I would say that the semi colon is the main flaw here in C. However, I would also say that E is a little clearer as to how these birds appear equal in size. In E you can see that it is "when they are seen" on a branch or in a nest.

With that said, I think that without the semi-colon choice C would be pretty good.

The statistics back me up on this. Since this is from the Question Bank and is currently in the "experimental stage" which means that it would NOT currently be eligible for any practice test until we have more data.

Here is what the stats show, nearly 3 times as many people have chosen C as compared to E. Only 20 percent of those who have tried this one have chosen the OA (E). This would seem to indicate a problem, right?

Well maybe not. The IRT curve shows that those who do answer correctly are also more likely to be high scorers. So the question might be flawed or it might just be very difficult. We need more data in order to know for sure.

As for your question about the actual GMAT and semi-colons - it is not something that I personally focus on...but it may well be a valid point as it appears to be mentioned by most sentence correction books.

I will be honest, when I looked at this one I was not sure I would like to see this on test day. We will have to see what the results tell us when we have more data in.

apoorva.rattan - you said,

IMO - there are a couple of problems with E.

...'appear equal in size when they are seen on a branch or in a nest'... Lacks clarity. Option C provides some of it by saying '....when sitting on a branch ....'.

Second, Option E does not clearly separate the second clause as does Option C.

Given that this does not seem to the OA, can someone point the error in my approach ? Also, an explanation of the approach/errors for the question.

I would say first that Option E does properly separate the second clause, but only because of the "while" - which subordinates the first clause and allows you to use a simply comma in that place. If you took of the word "while" C would then properly separate the clauses since neither clause would be subordinate.

As to the clarity, as you can see from the Explanation that I have copied above, clarity is one of the selling points of choice E. It is clear that it is to the observer that these birds look the same when they are in their nests and not to the birds themselves.

This is not about accuracy! Please remember this. There is no room on the GMAT for accuracy. Who knows what is accurate? If I say that Roger Federer is known for his soccer skills you might say that this is not accurate. But how do you know? Maybe he can bend a free kick like a pro. The point is that you are not supposed to evaluate what is accurate - so I am not saying that the birds do not appear to each other to be the same size. Maybe they do. What I am saying is that the construction of choices A B and D all lack clarity. It could be that the birds appear that way to each other or that they appear that way to the observer. Choice E is clear. It says, "when they are seen on a branch or in a nest" - so this clearly refers to any observer of the birds.

Again, let me reiterate, I would not like to see this one on test day.