a) To find the chromatic number of a graph we should look for the maximum sized clique i.e. a subgraph of a graph which is complete and contains maximum no of vertices i.e. contains K3 , K4 , K5 etc.So we can see that the maximal clique in the above graph is 3 . So 3 colours are sufficient to colour the entire graph such that no two adjacent vertices get same colour.Hence chromatic number of the given graph = 3.
b) Matching number is the set of maximal no of non intersecting edges.So here we can take (f,g) , (h,a) , (d,b) , (e,c) which are not intersecting with each other.Hence matching no = 4
Hence chromatic + matching no = 3 + 4 = 7
Hence , B) should be the correct option.