Which statement about public goods is most accurate?

• A. Public goods are non-excludable and non-rival; however, some non-excludable goods may be congestible or rival.
• B. Public goods are always provided efficiently by private markets.
• C. Public goods are excludable.
• D. Public goods never experience the free rider problem.

Answer: (A)

Public goods are defined by non-excludability and non-rivalry in consumption, meaning it’s hard to prevent people from using them and one person’s use doesn’t reduce another’s. Because of non-excludability, individuals have an incentive to free ride, so private markets tend to underprovide such goods. The statement also recognizes a useful nuance: even though public goods are non-excludable and non-rival in their pure form, there are non-excludable goods that can be congestible or rival, which means they’re not pure public goods but related cases like common resources or congestible types. The other choices are flawed: private markets do not always provide public goods efficiently due to the free rider problem; public goods are not excludable by definition; and they can indeed experience the free rider problem, so saying they never experience it isn’t correct.