I saw some trees the leaves of were black with disease. A. thatB. which C. itD. what

问题补充：

I saw some trees the leaves of were black with disease.

A. that

B. which

C. it

D. what

答案：

A. that

(答案→)B. which

C. it

D. what

解析：

B。the leaves of which 相当于 whose leaves。