1. If industrial pollution continues to deplete the ozone layer, the resulting increase in ultraviolet radiation will endanger human health, causing a rise in the incidence of skin cancer and eye disease, and perhaps even threatening global ecological systems.

(A) and perhaps even threatening

(B) and may even threaten

(C) and even a possible threat to

(D) as well as possibly threatening（B）

(E) as well as a possible threat to

i selected A ,why b??? please

will endanger human health and perhaps even threaten global eco. systems

causing .... 是同位语修饰 human health 的。

如果选 A 的话， endanger ..., causing ..., and threatening ..., 不能平行的。

如果你认为后面两个causing..., and threatening ... 并列的话，那么其间的逗号应该省略的呀。