Fill in the Blank: Qui est-ce ___ parle ?
Possibilities...

1. qu'
que becomes qu' in front of a vowel or silent h - which I don't think is the case here.
2. que
3. qui

So, I know que means what. For example, Que fais-tu ?
Likewise qui means who and we use it predominately when what we are looking for in the response is NOT the subject but receives the subject, right?

I apologize I just can't seem to grasp this concept...