经典题~我做过3次，选C吧？

首先你要知道what在这里的用法，有点特殊：
what + n.=all the + n.+ 关系代词
例如：I'll give you what help I can. = I'll give you all the help that I can.
在你的这句话中，what little可以理解为what little time

所以这句话可以转化为：
The home improvements have taken all the little time that there is of my spare time.

that there is是一个定语从句，你可以先不看。所以就是The home improvements have taken all the little time of my spare time.

我目前只能解释到这，你还有什么不懂的给我留言吧。