Is the United States a nation state or a multinational state?

The correct answer is B. Marginal cost is the money paid for producing one more unit of a good. Marginal revenue is the money earned from selling one more unit of a good.

Explanation:

Marginal cost and marginal revenue are two important concepts in economy and production especially to determine the cost and earning of a product and compare the cost or expenses and the earnings or revenue. Considering the cost is about the amount of money that implies producing something, the marginal cost refers to the cost for producing an additional unit, this cost also includes the technology and other elements that are required to produce the new unit. Similarly, the marginal revenue refers to the revenue or earnings from selling an additional unit of a product. As there should a balance between the money spend and the one earned ideally the marginal cost and the marginal revenue should be the same which means producing new units does not imply losing earnings.