The maximum number of binary trees that can be formed with three unlabeled nodes is:
Explanation: Following are all possible unlabeled binary trees
O / \ O O (i) O / O / O (ii) O / O \ O (iii) O \ O \ O (iv) O \ O / O (v)
Note that nodes are unlabeled. If the nodes are labeled, we get more number of trees.
We can find the number of binary tree by Catalan number number:
Here n = 3
Number of binary tree = (2nCn)/ n+1
= (2*3C3)/ 4+1
So, option (B) is correct.