Interrogative Pronoun
We use interrogative pronouns to ask questions. The interrogative pronoun represents the thing that we don't know (what we are asking the question about). There are four main interrogative pronouns: who, whom, what, which.
Examples
Whose book did you bring me?
When are the best days to go to the mall?
What kind of music do you want to dance to?
How many topics do you have to study?
Did we make a cake for you ?
What kind of music do you like?
Did you take your vitamin this morning?