Answer:
D. Euler Circuit.
Step-by-step explanation:
An Euler Circuit goes through every edge exactly once; starts and stops at the same vertex.
According to the Euler's Theorem, A graph has an Euler path if there are two 2-degree vertices without odd degrees and all other vertices have even degrees.
Mathematically, it is given as;
V+F=2-E
where;
F is the number of faces
V the number of vertices
E the number of edges.
