1. Country A and Country B can both produce cars and planes. If it is advantageous for both countries to specialize and trade, which of the following must be true?

A. One of the countries has an absolute advantage in the production of both goods.

B. The countries have different opportunity costs of production.

C. The opportunity costs of production are the same for both countries.

D. Opportunity costs for cars will be less than planes.

E. One country has an absolute advantage in the production of cars while the other has an absolute advantage in the production of planes.