¿Qué? vs. ¿Quién?

To ask a question, we use what = ¿qué es? when we are asking about one thing or one action. ¿qué son? when we are asking about many things. We use who = ¿quién es? when we are asking about one person and ¿quiénes son? when we are asking about two or more people.
Match the question word that you would use with the word on the left.