Concept:A credit note is issued by a seller to reduce the amount a buyer owes.Explanation:An overcharge means the buyer was billed more than the correct price. To correct this, the seller must reduce the buyer's debt by the excess amount. The seller sends a credit note, which records that the buyer has been credited for the overcharged amount. This document legally shows that the seller owes the buyer the corrected amount.Answer:B. a credit note