The photographs that the store developed were quite unsatisfactory. The customer claims to have handled the film correctly. Neither the film nor the camera was defective. If a store does not process pictures properly, the customer is owed a refund, so if the customer' s claim is correct, the store owes her a refund. The argument relies on assuming which one of the following? ['If neither the film nor the camera was defective, and the customer handled the film correctly, then the store processed it improperly.', 'If pictures are taken with a defective camera, then it is not possible for the store to develop those pictures improperly.', "If the customer's claim was not correct, then the store does not owe her a refund.", 'If the customer handled the film incorrectly, that is what caused the photographs that the store developed to be unsatisfactory.']