he referred to in his article was often discussed by many people.A. ThatB. WhatC. Whether

问题补充：

he referred to in his article was often discussed by many people.

A. That

B. What

C. Whether

D. Where

答案：

A. That

(答案→)B. What

C. Whether

D. Where

解析：考查主语从句。本题中的what引导主语从句what he referred to in his article并在句中作为refer to的宾语。句意：在他的文章中提到的事情经常被很多人讨论。That引导主语从句，只起引导作用，不能充当任何成分。Whether ,where不能在句中做主语或者宾语。故B正确。