most parents care about is to provide the best education for their children.A. ThatB. HowC

问题补充：

most parents care about is to provide the best education for their children.

A. That

B. How

C. What

D. Whether

答案：

A. That

B. How

(答案→)C. What

D. Whether

解析：考察从句连词选择。根据句子结构可知，该句为主语从句，作is 的主语。

从句中缺少care about的宾语，所以选择C