Question $2$ This question considers binary trees using the following node class. You may not assume that the tree has any method or additional fields. class Node $\{$ String key; Node left, right; $\}$ Node root; $//$ the root of the tree $($a$)$ Implement a method removeLeaves which removes all of the leaves in the tree, reducing the height by $1.$ public void removeLeaves $()\{($b$)$ If you assume that the tree is balanced, what is the order of growth for removeLeaves $()?$ Circle the best answer, where N is the number of keys in the tree.

$[1$ log N N N log N N$^2$log N $2^3]$