Question

The minimum number of colours required to colour the following graph, such that no two adjacent vertices are assigned the same colour, is

• A. 5
• B. 4
• C. 3
• D. 2

Answer 1

The correct option is B 4

An assignment of the colors 1, 2, 3 and 4 to the vertices of the graph is shown below such that the graph is properly colored.


So 4 colours are required.

(Note: The graph is a planar graph. The four colour theorem says that the chromatic number of a planar graph is at most = 4).