(2) (12 points) Let Kn be the complete graph on n vertices, and let Km,n be the complete bipartite graph with m and n vertices in each bipartition. (a) What is the size of a graph with degree sequence 6, 6, 5, 4, 4, 3, 3, 2, 1, 1, 1? _ (b) For what values of m and n, is Km,n Hamiltonian? (c) What is the (edge) chromatic index of K7,9? (d) What is the smallest possible number of vertices in a graph on 25 edges? 2