In informal speech yes, whatever sounds correct but it is not. The only correct answer here is 'whichever.'
We say 'whatever' when referring to a choice between a lot of different, or endless things. On the other hand, 'whichever' refers to a choice from a limited number of things.
Example: I have money. I can buy whatever I want.
I have money. I can choose whichever dress looked nice on me.
Student or Learner