It,s a pity that many people treat____the pupils do in spare time as something unimportantA thatB whatc whichD how

It,s a pity that many people treat____the pupils do in spare time as something unimportant
A thatB whatc whichD how

B
what 引导的名词性从句做宾语

...我错了，答案选B
It‘s a pity that many people treat（what the pupils do in spare time） as something unimportant
...(括号中指代这一现象，相当于the thing,作宾语)
遗憾的是许多人在对待（学生利用业余时间）（这一现象）不重视