求助GWD-3-Q28

荞麦皮

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


选E没问题。。
我的问题是。。冒号后边的句子主语是谁？一开始我觉得是the moose, 可是这样后边的it不就多余了么？如果the moose不是主语，那前边的这一串都是神马啊。。
along with... ...作为状语，the moose 怎么看怎么觉得是主语。。
混乱了 。。盼解答。。。

荞麦皮

荞麦皮