The core of the issue is parallelism; - call female moths - and -attract their mates - are the two functions that the male moths do and both of them should be parallel. The present participial -attracting -is wrong wherever it appears. The intrusion of a subject pronoun - they - is unnecessary in A and is a redundant use, in cases in which the subjects of both parts of the sentences remain the same

D is the answer
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D.
by the use of can be simply expressed by using
and last THEY in A is redundant. A and B out.

C is out because By atrracting is not correct usage. Even though we assume it were to keep parallelizm by must be used before using olfactory.

E. logically Call and Atract must be parallel.

The use of the verb 'call' should eliminate 'attracting'.

So, B,C & E out.

A - they attract is unnecessary. Just 'attract' will do.

D - My choice.

A clear parallelism question.
1. whistling = using
2. rather than
A. "by the use" - incorrect.
B. same as A.
C. by using sounds wrong.
Only D & E have "using". D is correct because it uses the idiom rather than (the same one that appears in the end of the sentence).

idea is to make "call" and "attract" parallel. Only option D does that.

(A) by the use of acoustical signals, but not olfactory ones, and they attract

(B) by the use of acoustical signals instead of using olfactory ones, and attracting

(C) by using acoustical signals, not using olfactory ones, and by attracting

(D) using acoustical signals, rather than olfactory ones, and attract

(E) using acoustical signals, but not olfactory ones, and attracting

=====================Hit kudos if it helped pls==============

I think that "by the use"is wrong grammatically, not idiomatic
we have to use 'with' before a noun to show a method of a main verb

I write with a pen
I learn gmat with a good spirit

we do not use "by" , anyone know, pls, show it here

we can use "by doing" or "doing" to show a method of a main verb in the main clause.

we can use "by" showing a method of a noun

the extraction by the use of chemicals is good
requirement by the program is high

those sentences possibly is correct

Correct option along with the non-underlined portion-

Scientists believe that unlike the males of most species of moth, the male whistling moths of Nambung, Australia, call female moths to them using acoustical signals, rather than olfactory ones, and that attract their mates during the day, rather than at night.

My doubt is that- Why we dont need THAT (marked in red) for parallelism?

It would be great if someone can clarify it.

Regards,
Tamal

Let us now parse this sentence.

1. Scientists believe --- The main clause

2. That -- a subordinate conjunction starting another dependent clause -- The 'that' here is a connector and not a relative pronoun.

3. unlike the males of most species of moth, ---- An introductory prepositional modifier

4. the male whistling moths of Nambung, Australia, call female moths to them using acoustical signals, rather than olfactory ones -- This is the first act of the subordinate clause sought to be introduced by the connector 'that', which we initially spoke about.


5. And attract their mates during the day, rather than at night. -- This is the second act done by the male moths. The parallelism lies between two verbs namely "call and attract."


If we now introduce another 'that' before attract, what will it refer to and more importantly be parallel to? If there is a verb after that' in any other place and if it is also done by the moths, then they will be parallel.

Actually, the intrusion of 'that' before attract, may only spoil the existing parallelism. You may notice the left part of 'and' is a clause while the right part is a noun -phrase.

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"by+noun" is not used to show the means with which action in the main clause is done. only some idioms allow this case
I go by plain/by train.

normally we use "doing" or "by doing" to show the means with which the action in the main clause is done. I think. both doing and by+doing are the same

I learn gmat by reading a lot.

"by use of acoustic signal" in choice A and B is not idiomatic.

This question tests you on the concept of parallelism.

The first clue here is the phrase ‘call female moths.’ This means that the next verb should agree with this form – simple present.
In other words, this is how the two actions/verbs will observe parallelism.

The sentence is saying that male whistling moths call using acoustical signals and attract their mates during the day.

It’s elegant to say ‘using’ instead of saying ‘by the use of’ – this is a matter of construction.

Let’s look at the options now:

(A) by the use of acoustical signals, but not olfactory ones, and they attract - Eliminate

(B) by the use of acoustical signals instead of using olfactory ones, and attracting - Eliminate

(C) by using acoustical signals, not using olfactory ones, and by attracting - Eliminate

(D) using acoustical signals, rather than olfactory ones, and attract

(E) using acoustical signals, but not olfactory ones, and attracting - Eliminate

Based on the two errors that are pointed out in red, we can eliminate Options A, B, C, and E.

Option D is the best choice.

Hope this helps!
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A and B are wordy

in between C, D and E, parallelism is only correct in D