大全251 there be

251.        Downzoning, zoning that typically results in the reduction of housing density, allows for more open space in areas where little water or services exist.

(A) little water or services exist

(B) little water or services exists

(C) few services and little water exists

(D) there is little water or services available（E）

(E) there are few services and little available water

C选项为什么不可以?即为什么此处要用there be 而不是exist?

原来是 0G107 利用转换表刚刚找到了。。不好意思了