It is reported that two schools are being built in my hometown will open next year. A.

问题补充：

It is reported that two schools, are being built in my hometown, will open next year.

A. they both

B. which both

C. both of them

D. both of which

答案：

A. they both

B. which both

C. both of them

(答案→)D. both of which

解析：both of which are being built in my hometown为非限制性定语从句，其中的which指代前面的two schools。