【求助】GWD3-Q28，句子结构不是很明白

The coyote is one of several recent ecological success stories:  along with the white-tailed deer, the moose, and other species that are enlarging their natural domains, they have established themselves as supreme adapters in an era when the capability to adjust to the environmental changes wrought by human beings has created a whole new class of dominant large mammals.

A.    they have established themselves as supreme adapters in an era when the capability

B.    they have established themselves as being supreme adapters in an era when being able

C.    it has established itself as a supreme adapter in an era when to be able

D.    it has established itself as being a supreme adapter in an era when its ability

E.     it has established itself as a supreme adapter in an era when the ability

我选择的是C，正确答案是E,请教NN们，能不能给我解释下，实在没明白句子结构......

The coyote is one of several recent ecological success stories(这段应该没问题吧):  along with the white-tailed deer, the moose, and other species that are enlarging their natural domains(状语, 里面嵌套定语从句), it (主语, 指代 coyote )has established(谓语) itself(宾语) as a supreme adapter(宾语补足语) in an era when the ability to adjust to the environmental changes wrought by human beings has created a whole new class of dominant large mammals.(时间状语, 里面嵌套定语从句)

明鸟...谢楼上滴GG，之前一直云里雾里的....