[SC. ]gwd 21-13

[kira12109 (三つ葉)]

Dolphins lack vocal cords, nevertheless creating sounds: a complicated system
of whistles, Squeaks, moans, trills, and clicks are produced by sphincter
muscles inside the blowhole.

A. nevertheless creating sounds: a complicated system of whistles, squeaks,
moans, trills, and clicks are produced by

B. nevertheless creating sounds: they produce a complicated system of
whistles,squeaks, moans, trills, and clicks with

C. but they do create sounds, producing a complicated system of whistles,
squeaks, moans, trills, and clicks with

D. but they do create sounds, a complicated system of whistles, squeaks,
moans,trills, and clicks being produced

E. but nevertheless creating sounds: a complicated system of whistles,
squeaks,moans, trills, and clicks produced by

想請問D答案,"a complicated...."是當前方sounds的同位語或是they的同位語呢?
對於對於同位語的指代對象總是弄不太清楚...

麻煩各位了!!

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推 denizee3:Sounds的同位語 這是Appositive modifer
→ denizee3:除非是abstract noun (strategy, figure, trend..etc)
→ denizee3:appositive 是modify the noun that comes immediately
→ denizee3:before the comma