这道有人争议过么, GWD-TN-10 Q41 - ChaseDream

GWD-24-41.
In California, a lack of genetic variation in the Argentine ant has allowed the species to spread widely; due to their being so genetically similar to one another, the ants consider all their fellows to be a close relative and thus do not engage in the kind of fierce intercolony struggles that limits the spread of this species in its native Argentina.

A.due to their being so genetically similar to one another, the ants consider all their fellows to be a close relative and thus do not engage in the kind of fierce intercolony struggles that limits

B.due to its being so genetically similar the ant considers all its fellows to be a close relative and thus does not engage in the kind of fierce intercolony struggles that limit

C.because it is so genetically similar, the ant considers all its fellows to be close relatives and thus does not engage in the kind of fierce intercolonystruggles that limits

D.because they are so genetically similar to one another, the ants consider all their fellows to be close relatives and thus do not engage in the kind of fierce intercolony struggles that limit

E.because of being so genetically similar to one another, the ants consider all their fellows to be a close relative and thus do not engage in the kind of fierce intercolony struggles that limits

我选D，答案选C。怎么看都是答案错了。
虽然前半句用的是the ant并且用的has，答案的it 可能是为了与前半句指代一致....但是怎么能说it is similar呢, 用法应该是 it is similar to ...或者 they are similar 吧？对象应该两个以上. 除此之外 struggles that limits 主谓不一致啊。。。
D 的they 虽然与前面的 the Argentine ant 单复数不一致，但是两句话中间分号隔开，后半句可以考虑为独立的句子了吧？因为
because they are so genetically similar to one another, the ants consider all their fellows to be close relatives and thus do not engage in the kind of fierce intercolony struggles that limit the spread of this species in its native Argentina. 这句单独看是没有错误的。 they代词往后指代 the ants 单复数也一致。

请NN指点。