Which of the following is an example of a common good? Cookies that are commonly consumed. Fish in the ocean. Lighthouses. Public schools.

The answer is fish in the ocean. Here's why: • Cookies: While they are common in everyday life, cookies are private goods. They are both excludable and rival (if you eat one, someone else can't have it). • Lighthouses: These are classic examples of public goods. They are nonexcludable (everyone can benefit from their light) and nonrival (one person's use doesn't reduce another's). • Public schools: Although they are run by the government and widely available, they are excludable in the sense that access can depend on residency, enrollment, etc., and they’re not typically considered common goods in the economic sense. • Fish in the ocean: Fish are often used to illustrate a common good (or common-pool resource) because they are nonexcludable (difficult to prevent anyone from fishing) but rival in consumption (catching a fish can reduce the number available to others). This characteristic can lead to overfishing, a phenomenon known as the "tragedy of the commons." Thus, fish in the ocean best fits the description of a common good.