The piece of evidence that would strengthen the argument that improvements can be made to buildings and towns to help contain fires is:
"These practices can be relatively inexpensive to perform."
This statement supports the argument by suggesting that the suggested improvements are feasible and accessible due to their cost-effectiveness. If these fire containment strategies are not prohibitively expensive, it would be easier to persuade homeowners, towns, and counties to implement them, thereby strengthening the case for making the improvements.