Concept:The debtors control account records total amounts owed by customers. A debit entry increases the total debtors balance.Explanation:Credit sales increase the amount customers owe the business.Therefore, credit sales are entered on the debit side of the debtors control account.Discount allowed, return inwards, and cash from debtors all reduce what debtors owe.Those items are entered on the credit side of the debtors control account.So, the only debit entry among the options is credit sales.Answer:C. credit sales