GWD语法题请教

melody远行

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 intercolony struggles 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
这题主要是想请教一下划线部分最后的那个单词limit到底是用单数还是复数？

5453

limit不就是修饰前面的struggles吗. 就应该是复数呀

滨江小陆

that就近指代struggles