Which + Noun(s)

Hey there,

Some grammar books say that which a singular noun, not plural nouns, can follow which to form a question. For example, "which sport do you like, basketball, baseball or volleyball?"

However, Sentences begining with "which+plural nouns" can be found on the Internet, like, "which ones bother you?"

So, I'm quite confused. Can someone help me figure them out?

Thank you!