Final answer:
The Twelfth Amendment requires that the president and vice president must come from different states, as electors cannot cast votes for a president and vice president from their own state. The correct answer is option d.
Step-by-step explanation:
According to the Twelfth Amendment, the statement which must be true about presidents and vice presidents is that the president and vice president must come from different states. This means an elector cannot cast votes for both a presidential candidate and a vice presidential candidate from the same state as themselves. The amendment stipulates that "The Electors shall meet in their respective states and vote by ballot for President and Vice-President, one of whom, at least, shall not be an inhabitant of the same state with themselves." The intention of this rule was to prevent electors from voting only for candidates from their own state, thereby encouraging a broader consideration of candidates from various states.