Correct Answer (Detailed Explanation is Below)
A.
Rotation
Detailed Explanation
When insertion causes an AVL tree to become unbalanced,
rotations are used to restore the required height balance while preserving the Binary Search Tree ordering property. The four common imbalance cases are
LL, RR, LR, and RL. LL is corrected using a right rotation, RR using a left rotation, while LR and RL require combinations of rotations. Rotations change the tree structure without changing the sorted order of its keys.