Concept:Selling on credit involves a risk that the buyer may not pay the amount due.Explanation:When goods are sold on credit, the seller allows the buyer to pay later.There is always a possibility that some buyers will delay payment or fail to pay entirely.Such unpaid amounts become bad debts for the seller.Bad debts are a loss to the business and are a major disadvantage of credit sales.Therefore, among the given options, the correct disadvantage is bad debts.Answer:D. bad debts