The diagram below illustrates an AVL tree. 12 9 19 11 14 21 10 20 39 On paper, draw the tree and calculate its balance factors after deleting the node with value 12. Then, answer the following questions: After deleting 12 (but before doing any rotations), how many nodes will no longer satisfy the AVL- invariant for balance? 0 On paper, perform all necessary rotations so that the tree maintains its AVL property. In the resulting tree: What is the parent of 20? [Select ] If you were to delete 20 (from the resulting tree after 12 has already been deleted and balance restored), what type of rotation would be needed to rebalance the tree? (Select ] If you were to keep 20 and instead delete 39 (from the balanced tree without the 12), what type of rotation would be needed to rebalance the tree? [Select ]