Question: What kind of can be used to model a highway system between major cities where
a) there is an edge between the vertices representing cities if there is an interstate highway between them?
b) there is an edge between the vertices representing cities for each interstate highway between them?
c) there is an edge between the vertices representing cities for each interstate highway between them, and there is a loop at the vertex representing a city if there is an interstate highway that circles this city?
