It’s thoughtful_____Mum____me pack my school bag so that I w

It's thoughtful_____Mum____me pack my school bag so that I won't forget anything.
A:for,helping B:for,to help C:of,to help D:of,helping 为什么选C不选其他的呢?

这个句考的就是thoughtful
看下面的解释以及例句：
1.深思的,沉思的
That put us all in a thoughtful mood.
这使我们大家陷入了沉思.
2.富有思想的;经认真推敲的
3.细心的,注意的[F][(+of)]
You should be more thoughtful of your behavior.
你应该更加注意你的举止.
4.体贴的,考虑周到的[(+about/of)]
She is always thoughtful of her mother.
她总是很体贴她的母亲.
分析：
1,thoughtful 后面只能接of,排除AB,详情问老师.
2,后面的动作是一般现在式,经常发生的动作,所以用help表示.