大全16-11 D中insect’s 的“S”是否多余？

11.   Like the color-discriminating apparatus of the human eye, insects’ eyes depend on recording and comparing light intensities in three regions of the electromagnetic spectrum.

(A) insects’ eyes depend on

(B) an insect eye depends on

(C) that of insects depend on the

(D) that of an insect’s eye depends on（D）
                     

(E) that of an insect’s is dependent on the

答案选D。我想问一个问题，D中insect’s 的“S”是否多余？我怎么也不明白

比如我把THAT还原就是Like the color-discriminating apparatus of the human eye,  the color-discriminating apparatus OF  insect eye depend on  recording 

如果insect’s是否多余呢

很愚笨的问题，请赐教