In the context of binary search trees (BSTs), consider the mystery method below. public class BSTTest { private static class Node { private int value; private Node left; private Node right; private Node(int value) { this.value = value; left right = null; } } private static class Counter { private int count 0; } private static class Counter { } private int count = 0; private static void mystery (Node node, int k, Counter counter) { if (node != null && counter.count The mystery method takes as argument the root node of a BST, a positive integer k, and a Counter object. When an instance of Counter is created, its value (count) is initially set to zero. What is the output of mystery (root, 2, new Counter(), when root is the root of the BST below? 7 2 L