prep 语法 一道关于情态动词的题

393075583

94.(29615-!-item-!-188;#058&003960)

The decline of the mountain yellow-legged frog in the high reaches of the Sierra Nevada has become severe enough for the United States Fish and Wildlife Service quite possibly to list it

as an endangered species in the near future.

(A) severe enough for the United States Fish and Wildlife Service quite possibly to list it

(B) severe enough so that the United States Fish and Wildlife Service could well list them

(C) severe enough for it quite possibly to be listed by the United States Fish and Wildlife Service

(D) so severe that the United States Fish and Wildlife Service could well list it

(E) so severe that they could well be listed by the United States Fish and Wildlife Service

D选项里的could well 是哪来的？可以随便添加情态动词嘛？
A选项里的possibly哪里去了呢？可以随便删掉吗？

谢谢各位了

Leliolevine

could well就是possibly的意思。。本题ABC用enough直接踢掉。。