The answer is D Costa Rica
The correct answer is air traffic controllers
Explanation:
A. Countries improve efficiency through producing goods in which they have the lowest opportunity cost.
B. Countries earn revenues from tariffs that are placed on imported goods
C. Companies gain the goods and services they need.
D. Host countries benefit by gaining jobs and tax revenue from multinational corporations.
Are these the options?
If so, answer is B.
I assume you mean WWI as there were only two. In WWI Americans participated. Many of the able men went to war. While the women, children, and disabled stayed and helped with the war effort. Most of the effort back home was from the women.