If International Trade Is Based on Product Differentiation, for a Country

If international trade is based on product differentiation, for a country the basis for:

A) exporting is the domestic production of unique models or varieties demanded by some consumers in foreign markets.
B) importing is that the price of the imports is the same as the price of the domestic products.
C) importing is that foreign firms usually enjoy external scale economies.
D) exporting is that the domestic producers can charge a much higher price in the international markets.