Final answer:
C. The impressment of US sailors by the British Navy.
The direct cause of the War of 1812 was the British practice of impressment, where American sailors were forced into service for the British Navy, leading to rising tensions and eventually to war.
Step-by-step explanation:
The direct cause of the War of 1812 was C. The impressment of US sailors by the British Navy. This aggressive practice involved the British Navy capturing American sailors and forcing them into service for the British, a violation of American sovereignty and a key factor leading to war.
Adding to tensions, British support of Native American resistance against American westward expansion and other unresolved issues from the Treaty of Paris also escalated the conflict. Despite attempts to avoid war, such as through Jay's Treaty, which sought to resolve matters like the evacuation of British posts in the Northwest, and the Embargo of 1807, the actions of British sea captains during the Napoleonic Wars left the U.S. with few options but to declare war.