What is an interrogative pronoun( IN BRIEF)
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
Notice that thepossessive pronounwhosecan also be an interrogative pronoun (an interrogative possessive pronoun).
subjectobjectpersonwhowhomthingwhatperson/thingwhichpersonwhose(possessive)