In the Ricardian model, there are two countries. The USA is designated as (U) and Canada is designated as (C). Assuming there is no international trade, if only two goods are produced (wine and cheese), the USA (U) would need to produce both goods in order to consume them. In this case, the USA would produce both goods:
a) only if the relative price of cheese is equal to its opportunity cost
b) only if the relative price of cheese is less than its opportunity cost
c) under all scenarios