Assume the key of the left child below the root node of a binary search tree is 30.The value in the root node could be ____.
A) 0
B) 10
C) 30
D) 40

Question

Quizplus · Accepted Answer

In a binary search tree, the left child of any node contains values less than the value in the node, and the right child contains values greater than the value in the node. Since the key of the left child below the root node is 30, any value less than 30 cannot be the root node. The key in the right child could be any value greater than 30. Among the given options, only option D (40) is greater than 30 and can be the value in the root node. Therefore, D is the best choice.

Assume the Key of the Left Child Below the Root