Answer : 1. "Dn = log 2 (n+1)"
Explanation :

Answer: A) Dn = log 2 (n+1) Explanation: A complete binary tree is a binary tree where all the levels have maximum number of nodes except possibly the last level.   The depth of complete binary tree of n nodes will be Dn=log 2 (n+1) where Dn is the height or depth of the tree and n is the number of nodes.