Which of the following is correct with respect to binary trees?

• A. Let T be a binary tree. For every k ≥ 0, there are no more than 2k nodes in level k
• B. Let T be a binary tree with λ levels. Then T has no more than 2λ – 1 nodes
• C. Let T be a binary tree with N nodes. Then the number of levels is at least ceil(log (N + 1))
• D. All of the mentioned