Any value of x greater than 5 will eliminate x from the cycle to which x belongs to. So we will be left with only two possible MST to include edge cost:4 of the extreme left node.
Similary, any value of x less than 5, will eliminate edge cost 5. So we will be again left with only two possible MSTs to include edge cost:4 as above.
Let's take the value of x=5, so this will give us
1. Two possible MSTs to include edge cost:4 for extreme left node.
ALSO
2 Two possible MSTs to include edge cost:5 for the extreme right node.
So total possible MSTs would be 4