[問題]PP3裡面的題目

[stwang]

Scientists believe that unlike the males of most species of moth, the male whistling moths of Namburg, 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

答案給(D)

這裡答案沒問題 可是我想請問一下using acoustical signals放在them的後面 是要修飾誰呢? 還是另有什麼功用?