-Are you familiar with the music?-Yes. There was a time this kind of music was quite pop

问题补充：

-Are you familiar with the music?

-Yes. There was a time this kind of music was quite popular.

A. that

B. when

C. with which

D. about which

答案：

A. that

(答案→)B. when

C. with which

D. about which

解析：句意：上文，你对音乐熟悉吗？下文，是的。有一段时间这种音乐很流行。这个句子中含有一个定语从句，且关系词在从句中作时间状语，故用关系副词when，选B。