8. Which of the following substantive audit procedures would not be an appropriate follow-up, when a positive confirmation sent, is not returned? 1. Examine cash received and credited to the customer's account subsequent to year-end. II. Vouch the recorded sale to the customer purchase order and the shipping documentation. Ic III. Mail a negative confirmation to the customer. IV. Place a phone call directly to the customer, asking them to respond to the confirmation or orally confirm Which of the following should an auditor gain an understanding of as part of the risk assessment