The course normally attracts 20 students per year,___up to half will be from overseas.

问题描述:

The course normally attracts 20 students per year,___up to half will be from overseas.
选项:A.in which B.for which C.with which D.of whom

D.of whom
先行词是students
把先行词代入从句,句子是
up to half 【of the students】will be from overseas.
他们中的一半来自海外
所以把【of the students】换成连接词就是 of whom