Our EMBA course normally attracts 200,000 students all over the

Our EMBA course normally attracts 200,000 students all over the country every year, （ ）up to 80% will be adult students.
A、for whom
B、with which
C、of whom
D、in which
【正确答案】：C
【题目解析】：句意：我们的EMBA课程通常每年吸引全国20万名学生，其中80%是成年学生。of whom up to 80%表示20万名学生中的80%。