Consider bipartite graphs. Let the left partition be L and the right, R. Prove or disprove each of the following statements:

(a) The sum of the degrees of the nodes in L must equal the sum of the degrees of the nodes in R. (b) The sum of the degrees of the nodes in R is even.

(c) The sum of the degrees of all nodes must be even. (d) Any graph that does not contain a triangle, C3, as a subgraph is bipartite.