In the given graph , we have 6 vertices .We know the conditions for MST :
a) In an MST , if we have n vertices ,we should cover all n vertices and we have n-1 edges
b) Also the sum of cost should be minimal
c) No cycle formation should occur in the MST
d) The MST should be connected.
So applying Kruskals algo , we choose the 3 edges having edge weights 1 so we need 2 more edges to be included in the MST.Now we have 3 edges available of edge weights 2 .But we can choose only those 2 edges containing edge weight 2 which are incident on vertex labelled u in the graph and we can not choose that edge which is incident on vertex labelled v as this will make the MST disconnected.
In short we have only 1 way to select minimum 5 edges to form the MST as mentioned above.
So no of MSTs possible = 1