The document indicating to the customer that the seller is reducing the amount owed by the customer is a:

A) credit memorandum.
B) sales discount.
C) customer allowance.
D) debit memorandum.

Credit Memorandum

A document issued to a customer by a seller, crediting the customer's account due to a return of goods or an overcharge.

Customer Allowance

A reduction in the selling price of goods or services, often granted to rectify complaints or fulfill contractual agreement terms.