Answer: 4) B and C only

• Binary Search Tree (BST): Not necessarily balanced; height can degrade to O(n).
• AVL Tree: Height-balanced by definition (balance factor −1, 0, +1); height is O(log n).
• Red-Black Tree: Enforces black-height properties that keep height O(log n); treated as a height-balanced binary tree.
• B-Tree: Balanced (all leaves at the same level) but not a binary tree; the term “height-balanced tree” typically refers to binary trees. Hence excluded here.