[求助]大全249

    Doctors still know little about how the Listeria bacterium is spread and why the disease it causes, listeriosis, afflicts some people in a contaminated area though it spares many others.

(A) though it spares

(B) where it spares

(C) despite sparing

(D) when sparing（E）

(E) while sparing

请问B哪里不对，谢谢

如果选B的话，那个It是不是有点指代歧义， Listeria bacterium 还是listeriosis？