For a country X producing only two products, A and B; when other things remain equal, points along the country's production possibilities frontier (PPF) can be used to show which of the following?

Choices

The opportunity cost of producing product A but not the opportunity cost of producing one unit of B.

The opportunity cost of producing product B but not the opportunity cost of producing one unit of A.

The opportunity cost of producing product only one product (i.e., A or B), but not the other.

None of the above.