(a) Show the result of every step of inserting the following sequence of elements into an initially empty AVL-tree: 10, 20, 15, 25, 30, 16, 18, 19. (b) Show the resulting AVL-tree, after physical deletion (NOT a lazy deletion) of the record with the key 30 from the AVL tree that you got in the previous exercise. (c) Show the result when an initially empty AVL-tree has keys 1 through 7 inserted in order (1,2,3,4,5,6,7).