— Who do you think should answer for Li Tianyi’s behavior? — Actually I think it is their

问题补充：

— Who do you think should answer for Li Tianyi’s behavior?

— Actually, I think it is their parents.

A. who are blamed

B. that are to blame

C. which are to blame

D. what are blamed

答案：

A. who are blamed

(答案→)B. that are to blame

C. which are to blame

D. what are blamed

解析：考查强调句和词组：句意：--你认为谁应该为李天一的行为负责？--实际上，我想他的父母应该受到责备。这句话是强调句：it is/was+强调句+that/who+其余部分，排除C，“应受责备”是be to blame，选B。