Actually in E, since "which...and which..." are modifying "green bloom", E suggests that the "green bloom" is produced over the course of time.

To me, from the original sentence, the intention seems to be to state that "Aerugo" is produced over the course of time.

If you take a moment to think about it, there is a difference in meaning.

From the original sentence, the intent is (and it seems logical to me):

a) Aerugo is the green "bloom" visible on many copper items
b) Aerugo is produced over the course of time by....

Aerugo, also known as verdigris, is the green "bloom" visible on many copper items, and is produced, like iron rust, over the course of time by the exposure of the metal to the oxygen in the atmosphere.

visible on many copper items, and is produced

that is visible on many copper items, and which produces

visible on many copper items, and produces

that is visible on many copper items, and that produces

which is visible on many copper items, and which is produced

In B, C and D, produces requires a direct object.
Since B, C and D do not indicate what the bloom produces, eliminate B, C and D.
The intended meaning is that AERUGO IS PRODUCED by the exposure of the metal.

In E, the second which refers to the green "bloom", implying that the BLOOM is produced by the exposure of the metal.
The intended meaning of the original sentence is that the subject of the sentence -- AERUGO -- is produced by the exposure of the metal.
Since E changes the intended meaning, eliminate E.

The correct answer is A.

Mitch, Please help.

I am little bit confused about the construction of the sentence. May be I am wrong.

Aerugo, also known as verdigris, is the green "bloom",visible on many copper items, ...........

I think there will be a comma before the word visible. I am not sure though.

sorry guys for digging this old post.

Mitch, is E also incorrect because of incorrect usage of which?
i.e which is used without comma here,
Asking because in this very discussion some poster has mentioned that GMAC now allows this construction.

Mitch, can you confirm ?

sorry guys for digging this old post.

Mitch, is E also incorrect because of incorrect usage of which?
i.e which is used without comma here,
Asking because in this very discussion some poster has mentioned that GMAC now allows this construction.

Can you confirm ?

aflaam wrote:sorry guys for digging this old post.

Mitch, is E also incorrect because of incorrect usage of which?
i.e which is used without comma here,
Asking because in this very discussion some poster has mentioned that GMAC now allows this construction.

Can you confirm ?

E: the green bloom which is visible on many copper items
The portion in red is composed of NOUN + which.

SC10 in the OG12:
A: a heat network which kept the brain from getting too hot
C: a heat network which has kept the brain from getting too hot
Here, the portions in red are also composed of NOUN + which.

OE in the OG12:
In (A) and (C), "which" introduces a restrictive clause. Some writers follow the convention that "which" can only be used for nonrestrictive clauses, but insistence on this rule is controversial.

The OE seems to allow for the usage of NOUN + which.
That said, GMAC has yet to publish an OA that employs this construction.
For this reason, I would be skeptical of an answer choice that includes NOUN + which.
My advice:
If an answer choice includes NOUN + which, look for an answer choice that avoids this construction.
If an alternate answer choice avoids NOUN + which and is free of errors, eliminate the answer choice with NOUN + which.

aditya8062 wrote:i had asked this thing to mitch and he said we can accept "which" without "comma". also he selected an option (another question) in which "which" was used without comma !!

Hi Mitch, a member, earlier in this thread, made the above comment.

Hence, the following statement confuses me. By any chance, do you recollect (or perhaps if aditya8062 could pitch in) as to which option aditya8062 is referring to, in the above comment where "which" was used without comma.

GMATGuruNY wrote: For this reason, I would be skeptical of an answer choice that includes NOUN + which.
My advice:
If an answer choice includes NOUN + which, look for an answer choice that avoids this construction.
If an alternate answer choice avoids NOUN + which and is free of errors, eliminate the answer choice with NOUN + which.

Hence, the following statement confuses me. By any chance, do you recollect (or perhaps if aditya8062 could pitch in) as to which option aditya8062 is referring to, in the above comment where "which" was used without comma.

i am on the ship at the moment and the internet onboard is really weak . it will get ok once i cross "cape of good hope" and i will repost that link

Thanks aditya8062 for replying even as you are on ship!

iongmat wrote:Hi Mitch, a member, earlier in this thread, made the above comment.

Hence, the following statement confuses me. By any chance, do you recollect (or perhaps if aditya8062 could pitch in) as to which option aditya8062 is referring to, in the above comment where "which" was used without comma.

I believe that aditya8062 is referring to the following SC:
https://www.beatthegmat.com/doubt-20-t280022.html
The source seems to be not GMAC but MGMAT:
https://www.manhattanprep.com/gmat/foru ... t1475.html
As I noted in my post above, no OA published by GMAC has ever included NOUN + which.
For this reason, I would follow the advice given in my post above.

Thanks Mitch. This helps!