Answer:
The graph must have 9 edges to be a tree ⇒ 3rd answer
Explanation:
* Let us explain how to solve the problem
- Tree with n vertices must have exactly n - 1 edges
- Tree is a connected graph with no cycles
- The edges of a tree are known as branches of the tree
- Look to the attached figure for more understand
* Lets solve the problem
∵ The graph has 10 vertices
∵ In the tree the edges less than the vertices by 1
∴ The number of the edges = 10 - 1 = 9 edges
* The graph must have 9 edges to be a tree