Which of the following statement is TRUE.

Statement A is FALSE: worst-case time complexity to find a key in a BST is O(n), not O(log n) (occurs when the tree is skewed/unbalanced). Statement B is TRUE: adding an element in a binary tree requires searching for the insertion position, which is O(n) in the worst case. Statement C is TRUE: in-order traversal of a binary search tree visits nodes in sorted (ascending) order by definition. Therefore, B and C are correct.

Step-by-step Derivation:
Analysis of each statement:

Statement A: Find in BST

• Best case: O(log n) on a balanced tree
• Worst case: O(n) on a completely skewed tree (like a linked list)
• FALSE - worst case is O(n), not O(log n)

Statement B: Add element in binary tree

• Must search to find correct insertion position
• In worst case, must traverse entire tree level by level
• Complexity: O(n)
• TRUE

Statement C: In-order traversal of BST

• In-order means: Left → Node → Right
• For BST: all left subtree values < node < all right subtree values
• In-order traversal visits in ascending order
• Example: BST [2, 1, 3] in-order gives [1, 2, 3]
• TRUE

Correct statements: B and C → Answer is B