Which of the following is NOT an independent verification control?

a. The shipping department verifies that the goods sent from the warehouse are correct in type and quantity.

b. Sales clerk verifies the creditworthiness of the customer before processing the sale.

c. General ledger clerks reconcile journal vouchers that were independently prepared in various departments.

d. The billing department reconciles the shipping notice with the sales invoice to ensure that customers are billed for only the quantities shipped.

e. All of the above are independent verification controls.