The major cause is the Germany was using submarines to sink down the American ships and killed all of the American soldiers, and that is why the U.S join the war and pay back... mark me brainlist please...
1. Gas industry
2. Retail industry
3. Transportation industry
Answer: what are your answers ?.
Explanation:
I'd say C because the other three wouldn't lead to it being the leading occupation, if anything, it would make it harder to conditions other than C
