(a) Given a graph G with N vertices, write a Matlab function with comments called 'connectcheck.m' to check the connectivity of the graph. The input should be the graph G and the output should be 1 if all vertices are connected and 0 if at least one vertex is not connected to the rest of the graph. [7 marks] (b) Does there exist a connected simple graph with 7 vertices and 4 edges? If yes draw one and if not, explain why not and discuss the minimal number of edges one must add to ensure that the graph is connected. [3 marks]