I should thank my friend Williams, ______originally suggested th

I should thank my friend Williams, ______originally suggested the idea for the publication.
A、who
B、whom
C、that
D、which
【正确答案】：A
【题目解析】：先行词为人时，关系代词用who/whom/that，在此句中关系代词充当从句主语引导非限定性关系从句，故用who。