Final answer:
The set of all actual and potential buyers of a product or service is referred to as a market.
Step-by-step explanation:
The correct answer is a. Market. In marketing, a market refers to the interaction between potential buyers and sellers. It is a combination of demand and supply, where buyers are the actual and potential consumers of a product or service. The market includes all individuals or organizations who have the ability and willingness to purchase goods or services.