Which of the following is a characteristic of a public good?

• A. It is excludable
• B. It is rival in consumption
• C. It is nonrival in consumption
• D. It has negative externalities

Answer: (C)

Public goods have the property that many people can use them at the same time without diminishing anyone’s ability to use them. That nonrivalry in consumption is the defining feature being tested here. When a good is nonrival, one person’s use doesn’t reduce another’s, so it’s not feasible to charge every user a price or exclude potential users without undermining the good’s value.

That’s why nonrival in consumption is the best description. Excludable goods can be restricted or priced, which isn’t typical of public goods. A good that is rival in consumption means one person’s use reduces another’s, which contradicts the idea of public goods. Negative externalities are about side effects on third parties and aren’t what distinguishes public goods. So the characteristic that fits a public good is nonrival in consumption.