Answer:
B. n-1
Step-by-step explanation:
If there are n vertices then that vertex can be origin of at most n-1 edges.Suppose that you have a graph with 8 vertices you can select a vertex from these 8 vertices now you have 7 other vertices.So the vertex you selected can have at most 7 edges or it can be origin of at most 7 edges.So we conclude that the answer is n-1.