What constitutional clause prohibits a state from drawing unreasonable distinctions between its own residents and those of persons living in other states?

The Privileges and Immunity Clause in the Constitution makes it known that citizens of one state visiting another state have the same rights as the citizens living in the state they are visiting. This clause was based on a provision In the Articles of Confederation that sought to establish fair treatment of everyone within the Union.

You don’t list any options but the one that frets overspending and the consequences of that.