Concept:Free goods are naturally abundant and available without payment or opportunity cost.
Explanation:A free good is not scarce and has zero opportunity cost for society.
It exists in such plenty that everyone can enjoy it without reducing its availability to others.
Air is a common example of a free good.
Education, even when free, involves teachers and buildings, so it uses scarce resources.
A dinner you did not pay for was still produced at a cost, and a rented apartment is rented because it is scarce.
Water in the ocean is naturally vast and not owned, so consuming some does not create scarcity or opportunity cost.
Answer:B. Water in the ocean