One result of the war of 1812 was that the united
states
(1) acquired french-held territory in southern
canada
(2) maintained its independence and its territory
(3) lost control of the ohio river valley
(4) gained territory from mexico

The best answer is (2).

Though suffering some bad losses and defeats, America also scored some crucial victories over the British especially on Lake Erie and Lake Champlain. It was these victories that made England agree to a peace treaty in 1814 and thus America retained her independence and territory. The main benefit for the U.S. was a renewed self confidence and faith of its military to defend the nation's freedom and honor despite the fact that neither side came away with a clear cut victory.

assessment is the missing word

it was the "4. potsdam" conference that demanded the unconditional surrender of japan, since it was clear that the japanese would continue to find until the very last man otherwise.