Which term best describes a good that is non-excludable but rivalrous, such as rival natural resources?

• A. Pure public good
• B. Private good
• C. Common resource
• D. Club good

Answer: (C)

The key idea is a good that cannot be easily kept out from others but whose use by one person reduces the amount available for everyone else. This describes a common resource: you can’t easily exclude people from using a shared natural resource, but each use diminishes what others can use. Think of fish in a shared lake or grazing land—open access leads to overuse unless managed, a concept often called the tragedy of the commons.

Pure public goods are non-excludable and non-rivalrous, so they don’t fit because this resource is rivalrous. Private goods are excludable and rivalrous, so they’re not non-excludable. Club goods are excludable and non-rivalrous up to a point, so they’re also not non-excludable in the sense required here.

Therefore, the term that best describes a good that is non-excludable but rivalrous is a common resource.