He thought mattered most in improving your spoken English was en

He thought mattered most in improving your spoken English was enough confidence and practice.
A、Why
B、What
C、Which
D、That
【正确答案】：B
【题目解析】：考查宾语从句的连接词。此处what作宾语从句的主语。句意：他认为提高英语口语的关键是有足够的信心和练习。