Answer
Since the graph has exactly two odd vertices, the graph has at least one Euler path. Therefore, it is possible to visit the four areas using each bridge or tunnel only once.
Work Step by Step
We need to verify the number of odd vertices in the graph.
The vertex for Manhattan has 9 vertices.
The vertex for Long Island has 7 vertices.
The vertex for Staten Island has 4 vertices.
The vertex for New Jersey has 6 vertices.
Since the graph has exactly two odd vertices, the graph has at least one Euler path. Therefore, it is possible to visit the four areas using each bridge or tunnel only once.
