Which of the Following Is a Statement That Supports the Theory

Which of the following is a statement that supports the theory of comparative advantage?

A) International trade is a zero-sum gain where one nation's gain is another's loss.
B) Domestic industries are at risk when a country engages in free trade.
C) A country should maintain a trade surplus to succeed in global trade.
D) Global production is greater with free trade than it is with restricted trade.