What is the consumer surplus for a purchase where the consumer pays exactly what they are willing to pay?

Consumer surplus is defined as the difference between what a consumer is willing to pay for a good or service and what they actually pay. When a consumer pays exactly the price they are willing to pay, there is no difference or surplus generated from the transaction. In this scenario, the consumer's willingness to pay matches the market price, resulting in a consumer surplus of zero. Therefore, the correct answer is that the consumer surplus is indeed zero, reflecting that the consumer does not gain any additional benefit beyond their expenditure.