161. A wildlife expert predicts that the reintroduction of the caribou into northern Minnesota would fail if the density of the timber wolf population in that region is more numerous than one wolf for every 39 square miles.

(A) would fail if the density of the timber wolf population in that region is more numerous than

(B) would fail provided the density of the timber wolf population in that region is more than

(C) should fail if the timber wolf density in that region was greater than

(D) will fail if the density of the timber wolf population in that region is greater than（D）

(E) will fail if the timber wolf density in that region were more numerous than

D

如果B改成(B)will fail provided the density of the timber wolf population in that region is greater than对吗？

provided 和if 表示条件有什么区别呐？