Looks correct to me, but you may want to state the thought process at each step. Show the choices and explain why other edges are not available. For example:
X is adjacent to edges with values 4 and 12. We choose the edge with least value: 4
This gives us two vertices adjacent to edges with values 1, 6, 7, or 12. Choose 1.
Now, the adjacencies have values 5,6,7,12, choose 5.
This gives adjacencies to edges with values 6,7, 9, 12, 14, but 7 connects two vertices already contained in the tree, so it is not available. Choose 6.
Next, the adjacent edges have values 3, 7, 9, 11, 12, 14. The edges with values 7 and 14 connect vertices already in the tree, so we ignore them. Choose 3
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