The best answer that describes the effect of World War I on the economy of both the US and Oklahoma is:
B. The nation prospered as the US was one of the few countries able to send goods to Europe during the war.
During World War I, the US economy benefited from increased demand for agricultural and industrial goods, as many European nations were involved in the war and their own production was disrupted. This allowed the US to become a significant supplier and see economic growth during the war period.