It was nine years ago, when I came to China for the first time ____ I began to??? learn Chinese.

A. where??????? B. how???????? C. that???????? D. which????????

 It was nine years ago, when I came to China for the first time, __________ I began to learn Chinese.
    A. where           B. how               C. which         D. that

 It was nine years ago, when I came to China for the first time, ______ (我开始)learn Chinese. (begin)