Which of these was a major source of conflict between President John Adams and Vice President Thomas Jefferson?

A) Thomas Jefferson opposed the Alien and Sedition Acts passed by the Federalist Congress.

B) Adams strongly supported the Virginia and Kentucky Resolutions while Jefferson opposed them.

C) Adams was sympathetic to the French Revolution while Jefferson opposed supporting this event.

D) Thomas Jefferson wanted to be the face of the Federalist party and felt that Adams was not qualified to lead.

A) Thomas Jefferson opposed the Alien and Sedition Acts passed by the Federalist Congress.

The major source of conflict between President John Adams and Vice President Thomas Jefferson was that Thomas Jefferson opposed the Alien and Sedition Acts passed by the Federalist Congress, because towards the elections of 1796 the candidate that won the elections was the Federalist John Adams, and the Democratic-Republican Thomas Jefferson came in second place, for that reason and due to the laws of that time, John Adams became in President and Thomas Jefferson became in Vice - President, but Jefferson didn't agree to the Federalist and decidedly opposed to the Federalist proposals, primarily he opposed to the Alien and Sedition Acts, whereby it was generated a conflict between Adams and Jefferson that caused the nation polarization.

So, according to the previous, the right answer is option A) Thomas Jefferson opposed the Alien and Sedition Acts passed by the Federalist Congress.