1. In an argument, what is used to prove a claim?

Evidence.

Explanation:

Evidence is the concrete facts used to support a claim. ... Many arguments begin by treating something as a claim, try to prove it, and then, once they have proved it to the author's satisfaction, treat it as a fact to be used as evidence to support some new claim.

our founding fathers introduced the revolutionary idea that each person's desire to pursue their idea of happiness was not self-indulgence, but a necessary driver of a prosperous society. they created a government to defend that right for everyone.