Which element of graph theory specifies a subgraph of a graph by allowing the incidence of exactly two branches at each node?

a. Twig

b. Path

c. Loop

d. Link

ANSWER: Loop

Explanation:

According to the properties of a loop, it ensures the presence of at least two branches in addition to exactly two paths between any pair of nodes in it .Besides these, the number of branches are always equal to the number of nodes and hence, the two branches are exactly incident at each node.