find a minimum spanning tree for the weighted graph using kruskals algorithm

You are a discrete structure engineer in a well know organization, your boss has requested you to find/figure-out all non-isomorphic trees with four vertices.

Show that the number of vertices in a binary tree is odd. Also calculate the forinula for the number of pendant vertices in a binary tree.

Consider the relation on A = {a, b, c, d, e} given by R = {(a,b), (b,c),(b,d), (b,e),(d,e)}