16. Which department does not receive a copy of a purchase order? a. Purchasing department b. General ledger c. Receiving department d. Accounts payable 17. Which document initiates the revenue cycle? a. Sales invoice b. Sales order c. Journal voucher d. Customer's purchase order 18. When should a customer be billed for a back order? a. When original goods are shipped b. When the purchase order is received c. Customer is not billed for back orders