# Question :

Which of the following is true about Binary Trees?

A. Every binary tree is either complete or full.

B. Every complete binary tree is also a full binary tree.

C. Every full binary tree is also a complete binary tree.

None of the above

# Solution :

D) is correct.

`A full binary tree is a tree in which every node other than the leaves has two children. A complete binary tree is a tree in which every level, except possibly the last, is completely filled, and all nodes are as far left as possible.A) is incorrect. For example, the following Binary tree is neither complete nor full                             12                            /                           20                          /                         30B) is incorrect. The following binary tree is complete but not full                             12                            /  \                           20   30                          /                         30C) is incorrect. Following Binary tree is full, but it is not complete                             12                            /  \                           20   30                          /       \                         20        40D) is correct. As all above options are incorrect.`