What follows is a GMAT question.
The key answer is D.Scientists believe that unlike the males of most species of moth, the male whistling moths of Nambung, Australia, call female moths to them by the use of acoustical signals, but not olfactory ones, and they attract their mates during the day, rather than at night.
(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
I wonder why "by" is not needed and why "using acoustical signals" is not set off by a comma before "using."
If you have 'by' in there, what is the function of 'but'? It would be unnecessary as there is 'unlike' earlier on to show the difference between the species and 'rather than' to show how it differs. I think you could have a comma, but it's optional.
i think if u use by using it leads to redundance.... plzzz correct if i am wrong
Rather correctly shows the relationship and also is is parallel with "rather than...".
The GMAT tests certain things, and unfortunately for for students who aren't native English speakers, this can be difficult, especially when it comes to idioms and parallelism.
The Manhattan GMAT sentence correction guide is excellent for helping spot these issues. I used it in my GMAT studies and found it sufficient.