a. Show that via AVL single rotations, any binary search tree T1 can be transformed into another

Question:

a. Show that via AVL single rotations, any binary search tree T1 can be transformed into another search tree T2 (with the same items).
b. Give an algorithm to perform this transformation using O(N logN) rotations on average.
c. Show that this transformation can be done with O(N) rotations, worst case.