Which of the following properties are true for binary trees? Choose all that apply Here, h is the height of a binary tree and n is the number of nodes in a binary tree. a. The height of a binary tree is at most n - 1. b. The number of external nodes in a binary tree is at least 2. O c. The number of nodes in a proper binary tree is at most 2h+1 Od. The number of internal nodes in a proper binary tree is at most 2h-1