Final answer:
A well-maintained waterfront property enjoyed by others is a positive consumption externality because it benefits third parties who are not involved in its upkeep.
Step-by-step explanation:
A well-maintained waterfront property that is enjoyed by other property owners is an example of C) a positive consumption externality. Externalities are consequences of economic activities experienced by unrelated third parties; they can be positive or negative. When an externality benefits a third party, it is termed positive. In this case, the enjoyment other property owners derive from the well-maintained waterfront property is an additional benefit they receive without being directly involved in the maintenance or ownership of the property, hence, it's a positive externality. A well-maintained waterfront property that is enjoyed by other property owners is an example of a positive consumption externality. A positive consumption externality occurs when a third party benefits from someone else's consumption activity. In this case, the other property owners benefit from the enjoyment and aesthetic value of the well-maintained waterfront property.