What Does the Concept of Comparative Advantage Show

What does the concept of comparative advantage show?

A) One party with an absolute advantage in producing two different goods may export both of those goods to the other party.
B) One party may be able to produce everything relatively more efficiently than another party.
C) One party may be able to produce something at a lower dollar cost than another party.
D) One party may be able to produce something at a lower opportunity cost than another party.