Which of the Following Phenomena CANNOT Be Explained by the Simple

Which of the following phenomena CANNOT be explained by the simple comparative advantage theory?

A) A country that does not have much farmland tends to import agricultural goods.
B) A country with a lot of skilled labor tends to export highly technical goods.
C) A country tends to export the goods that it can produce at a lower opportunity cost.
D) A country imports and exports the same goods.