Final answer:
The United States declared war on Great Britain in 1812 mainly because of impressment of American sailors by the British navy and their support for Native American resistance against U.S. expansion, leading to the War of 1812.
Step-by-step explanation:
The United States declared war on Great Britain in 1812 due to several reasons including the British navy repeatedly seizing American merchant ships and impressing their sailors into service (response D). This practice of impressment was one of the unresolved issues left over after Jay's Treaty in 1794 and was particularly exacerbating to the Americans.
Furthermore, the British naval captains, needing to reinforce their ranks during the Napoleonic Wars, took American sailors to meet this need, despite opposition from the British government to a war with the United States. The situation was further aggravated by British actions in Canada, where they supported Native Americans against U.S. expansion, prompting calls for war led by 'war hawks' such as Henry Clay and John C. Calhoun. Despite the controversy and opposition from Federalists, Congress authorized the declaration of war in a narrow vote.