In an AVL tree, after inserting a new node, node X becomes unbalanced with a balance factor of +2 (right subtree taller), and X's right child also has a balance factor of +1 (also right-heavy). Which rotation should be performed to restore balance at X?

A balance factor of +2 at node X (right subtree taller by 2) combined with the right child also being right-heavy (+1) is the classic "Right-Right" (RR) imbalance case. This specific pattern is corrected with a single Left Rotation at X, which promotes X's right child to take X's place, making X the new left child of that former right child. (If the right child had instead been left-heavy, this would be the more complex "Right-Left" case, requiring a double rotation — first right on the child, then left on X.) A balance factor of ±2 is, by definition, outside the AVL tree's allowed range of {−1, 0, +1}, so a rotation is required, ruling out option E.