A Binary Search Tree Is Made Up of a Collection

Multiple Choice

A binary search tree is made up of a collection of nodes organized with smaller data values on the left and greater values on the right, relative to any node. Which of the following Node references must be instance variables of any implementation of a BinarySearchTree class?
I root
II left
III right

A) I
B) II and III
C) I and II
D) I, II and III