In the Real World We Don't Observe Countries Completely Specializing

Multiple Choice

In the real world we don't observe countries completely specializing in the production of goods for which they have a comparative advantage.All of the following are reasons for this except

A) not all goods and services are traded internationally.
B) some countries have more resources than other countries.
C) tastes for many traded goods are different in many countries because of globalization.
D) production of most goods involves increasing opportunity costs.