If Two Countries Had Completely Free Trade with Each Other,why

If two countries had completely free trade with each other,why might a multinational corporation still be created such that it holds factories in both countries?

A) The multinational corporation wants to gain access to markets to which it would not otherwise have access.
B) Multinational corporations generally receive better treatment abroad than in their home countries.
C) Both countries have similar regulatory burdens.
D) The multinational corporation wants access to cheaper labor in one of the countries.