GRAPH COLORING fine the chromatic number of these graphs nee

GRAPH COLORING. fine the chromatic number of these graphs
need help with k,l,m please

Solution

(k) The center vertex c is connected to four other vertices, hence the chromatic number of the graph will be minimum 5 in order to properly color the graph

(l) The bottom and top vertex is connected to four other vertices, hence the chromatic number of the graph will be 5

(m) Each vertex is connected to other four vertices, hence the chromatic number of the graph will be equal to 5