For an undirected graph with n vertices and e edges, the sum of the degree of each vertex is equal to

For an undirected graph with n vertices and e edges, the sum of the de

1.	For an undirected graph with n vertices and e edges, the sum of the degree of each vertex is equal to
A.	2n
B.	(2n-1)/2
C.	2e
D.	4n
Answer» D. 4n