What is the definition of a chargeback?

A chargeback refers to a situation where a customer disputes a transaction and requests the reversal of that transaction, typically due to unauthorized use, dissatisfaction with the product or service, or failure to receive the item purchased. In this context, option B captures the essence of a chargeback as it involves a dispute that leads to the holding of funds in a merchant's account until the transaction is resolved. This is a protective measure for consumers allowing them to dispute charges they believe were made in error or fraudulently.

While other options mention related concepts, they do not accurately define what a chargeback truly represents. A refund for a returned item implies a simple transaction reversal initiated by the merchant rather than a dispute, while the merchant's approval of a transaction after the fact indicates a post-transaction action, not a dispute. Lastly, a bonus from the acquirer is unrelated to the chargeback process and more focused on incentives for sales performance. Hence, option B is the clear and correct definition of a chargeback within the context of payment processing.