Why did rival candidates become president and vice president ?

it's a political move.

Explanation:

they can win over other members of their party who may have supported the VP pick by teaming up with them even though they ran against in their primary.

it's a way to maximize voter turn out for their base.

I believe they did that because that was the election process in the original Constitution. They changed it because of the 12th amendment (ratified in June 1804. Just in time for the next election)

they gained popular support by speaking out against communists

in the united states. ( d.)

i think the answer is the one about environmental and social health.

hope this