proof techniques – Inductively prove that the complete recursion tree to calculate the nth number of Fibonacci a n leaves

I'm struggling a bit with this homework question. I've referenced this similar question: Prove the accuracy of the recursive Fibonacci algorithm, using induction proofing

I'm just trying to build an induction proof to show that the recurrence tree for the nth fibonacci number would have exactly n leaves. I understand the basic trivial case, I am trying to design the inductive hypothesis. If anyone could point me in the right direction, I would be extremely grateful to you.