(13) (2 points) Is the following a valid AVL tree? 4 3 5)3 2 6 (a) Yes (b) No. Node 3 is unbalanced (c) No. Node 4 is unbalanced (d) No. Node 7 is unbalanced. (e) No. A different node is unbalanced (14) (2 points) If 3 is inserted into the following Red-Black tree, what are the colors of 2 and 3? (Red nodes are colored white.) 4 6 (a) 2: Black, 3: Black (b) 2: Black, 3: Red (c) 2: Red, 3: Red (d) 2: Red, 3: Black (e) One of the nodes is not in the tree (15) (2 points) What additional structure would you use to help determine if a singly- linked list is a palindrome? (A palindrome retains the same order if the list is re- versed (a) Queue (b) Dictionary (c) Stack (d) Heap (e) No additional structure is necessary