Q$10.$ In network theory, the hand$-$shaking theorem states that $(2$p$.)$

a$)$ The sum of the degrees of all vertices in an undirected graph is twice the number of edges in the graph.

b$)$ The number of vertices in an undirected graph is always even.

c$)$ The sum of the degrees of all vertices in a directed graph is equal to the number of vertices. d$)$ The number of edges in an undirected graph is equal to the number of vertices.

e$)$ The sum of the degrees of all vertices in an undirected graph is always odd