Concept:A debit note is used to increase the amount a buyer owes to the seller.Explanation:An undercharge means the seller charged less than the correct amount on the invoice.To fix this, the buyer’s account must be increased by the extra amount owed.A debit note is the document issued to record and correct this undercharge.A credit note would be used for an overcharge or a reduction, not for an undercharge.Answer:B. debit note