Question 4 Consider the following binary tree method for a tree with keys of type Key, which is an object type. (a) In plain English, describe the function of mystery(). (This should be a short, clear answer. Zero credit for describing the code line by line!) (b) If you assume that the BST is balanced, what is the order of growth for mystery () ? Circle the best answer, where N is the number of keys in the tree. 1logNNNlogNN2N2logNN32N