I don't like _ when people talk with their mouth full.

I don't like it when people talk with their mouth full
it指代后面的事情
我不喜欢别人说话时嘴巴含着东西。

准确的来说，这是个从句

我不喜欢和人们谈话时,嘴巴里含着食物.

it
这是单选吧？