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. (E)

1. they have established themselves as supreme adapters in an era when the capability
2. they have established themselves as being supreme adapters in an era when being able
3. it has established itself as a supreme adapter in an era when to be able
4. it has established itself as being a supreme adapter in an era when its ability
5. it has established itself as a supreme adapter in an era when the ability

我知道这题因为it指代前面的the coyote而排除了A和B。但我想请教一下这个句子里前面The coyote is ...和后面it has established itself as...之间的关系是什么？不需要在it之前加上连词吗？我总感觉两个句子联系不够紧密？请NN指点，谢了！