I know it’s not important, but I can’t help __about it.

I know it’s not important, but I can’t help __about it.
A、to think
B、and think
C、thinking
D、being thought
【正确答案】：C
【题目解析】：can't help表示“忍不住”，后面接-ing形式；表示“不能帮助”时，后面接不定式。