Concept:An invoice is a commercial document that states the amount a buyer must pay for goods or services.Explanation:A supplier sends an invoice to a prospective buyer before or after a sale.It lists the items, their prices, and the total amount payable.This document clearly informs the buyer of what to pay if the purchase is made.Other options do not match: a credit note reduces an amount owed, an advice note simply announces a shipment, and a debt note is not the standard term here.Answer:C. invoice