1. Beef exports in the US dropped because Argentina could produce beef at a lower cost after refrigeration was invented. Refrigeration made it possible to ship meat over long distances, so Argentina became more competitive in the world market.
2. Argentina gained because its beef industry expanded and exports increased. Consumers in many countries benefited from cheaper beef. US beef producers lost because they could not compete with lower-cost Argentine beef.
3. Primary industry: Cattle farming
Secondary industry: Meat processing and packaging
Tertiary industry: Transportation, marketing, and retail sales
4. The US should specialize in beef, while Argentina should specialize in corn. The US gives up less corn when producing beef, and Argentina gives up less beef when producing corn. By specializing and trading, both countries can gain from comparative advantage.