Explain why performing a rotation in an n-node binary tree

Question

Problem

1. Explain why performing a rotation in an n-node binary tree represented using an array list takes ?(n) time.

2. An alternative way of performing a split at a node v in a (2,4) tree is to partition v into v ′ and v ′′, with v ′ being a 2-node and v ′′ a 3-node. Which of the keys k₁, k₂, k₃, or k₄ do we store at v's parent in this case? Why?