Answer:
1859
Explanation: Petroleum became a major industry following the oil discovery at Oil Creek, Pennsylvania, in 1859. For much of the 19th and 20th centuries, the US was the largest oil producing country in the world.
Its C because as u can tell the angle of the diagram is pointed in that angle
Well because of the great depression many factories were just lying around not producing anything but when the us as attacked by japan almost immediately those factories were up and running to make war supplies and they needed workers so almost no unemployment in the us and everyone was making money.
Maybe because we are getting free answers
