I stayed in Japan only a few matches,, I went through a series of hardship.A. during when

I stayed in Japan only a few matches, , I went through a series of hardship.
A. during when
B. at that time
C. during which time
D. of which time

A. during whenB. at that time (答案→)C. during which time D. of which time解析：考查定语从句，介词+which的用法，先行词是a few matches，说明是在那段时间，用during，which指a few matches，句意是：我只在日本呆了几场比赛，在那段时间，我经历了很多困难。选C。

感谢回答，我学习了