Which of the Following Controls Ensures the Accuracy of Transactions

Which of the following controls ensures the accuracy of transactions in the revenue process?

A) Every transaction is reviewed at the end of the month.
B) Independent checks should be made to ascertain that the correct prices are being charged to pre-approved customers.
C) Invoice quantities and amounts should be verified against the sales order and shipping records, with discrepancies reported if over a certain amount.
D) All of the above ensure the accuracy of transactions in the revenue process.