Recall the definition of a binary search tree: a binary tree is a binary search tree if: - It is a nullptr - It is not a nullptr, has a key, and: - The left-hand child is a binary search tree, all of whose keys are less than this node's key. - The right-hand child is a binary search tree, all of whose keys are greater than this node's key. (a) There are five possible binary search trees (down to isomorphism) with three nodes. Draw them. (b) There is only one possible binary search tree of size one (one vertex), there are two of size two, five of size three, and 14 of size four. Use this information to determine how many binary search trees of size five are possible. An answer that does not use this information in a meaningful way to solve the problem will cause you to receive zero credit for the entire