Answer:
F: The revolutionary war. This is the only answer that dates this close to the date provided in the question (1850). It can't be the war of 1812, because that is way earlier than 1850. The U.S.-American war was in like 1830 something, and it can't be the civil war, because that was closer to the 1900's. So the only answer left that is even remotely close to 1850 is the revolutionary war.