(20%) Answer the following questions about binary search trees (BSTs). (a) Draw the final BST after inserting elements 20,25, 7, 16, 19, 23, 17,31, 18, 6, 12, 4, 5, 14, 21 in that order. (b) Draw the tree after deleting 23 from the BST in (a). (c) Draw the tree after deleting 25 from (b). (d) Draw two trees after deleting 16 from (c) using (1) the largest element in the left subtree; (2) the smallest element in the right subtree. (e) List the elements of pre-order, in-order, and post-order traversals of the tree from (d)(1)