SInce complete graph,that means an edge between every pair of vertices.

Using Kruskal first we have to choose an edge with weight 1 after that with weight 2,now we can use weight 3 to make a cycle in the graph, thus kruskal will ignore that edge,so next edge with weight 4 have to be chosen which gives us the MST with maximum weight of (1+2+4)=7.

7?

explain properly pls

SInce complete graph,that means an edge between every pair of vertices.

Using Kruskal first we have to choose an edge with weight 1 after that with weight 2,now we can use weight 3 to make a cycle in the graph, thus kruskal will ignore that edge,so next edge with weight 4 have to be chosen which gives us the MST with maximum weight of (1+2+4)=7.