1. A S-graph is a connected graph G = (V, E) in which every vertex has degree 5 and in which there are no loops and there is at most one edge between any two vertices. For example, the complete graph K6 is a 5- graph. a) Given an example of a Sgraph with 10vertices. (It is enough to draw the graph.) b) Using the degreeedge equation, or otherwise, show that 5|V| = 2|E |. c) Hence, deduce that the number of vertices in a Sgraph is always even and that the number of edges is always divisible by 5. d)* Show that a Sgraph can never be a tree