According to opportunity costs, should specialize in petroleum. According to opportunity costs, should specialize in seafood.

The answer is below

Explanation:

According to opportunity costs, COUNTRY A should specialize in petroleum.

According to opportunity costs, COUNTRY B should specialize in seafood.

This is because, based on the data in the table, the opportunity cost for Country A to produce 16 units of petroleum is 8 units of seafood.

And the opportunity cost for Country B to produce 8 units of petroleum is 8

units of seafood.