In a BST, what is the minimum number of nodes required to form a tree with a height of 3?

In a Binary Search Tree (BST), the minimum number of nodes required to form a tree with a height of 3 is 4. Here's the step by step explanation:

1. The height of a tree is the maximum distance from the root node to any leaf node. In a BST, each node has at most two children - a left child and a right child.

2. A tree with a height of 0 has only 1 node, which is the root node itself.

3. A tree with a height of 1 has a minimum of 2 nodes - the root node and one of its children.

4. A tree with a height of 2 has a minimum of 3 nodes - the root node, one of its children (which is also a parent node), and a child of that child node.

5. Therefore, a tree with a height of 3 has a minimum of 4 nodes - the root node, a child of the root (which is also a parent node), a child of that child (which is also a parent node), and a child of that child node.

So, the minimum number of nodes required to form a BST with a height of 3 is 4.