Which of the following controls most likely would ensure that all credit sales transactions of an entity are recorded?

a. the billing department supervisor sends copies of approved sales orders to the credit department for comparison to authorized credit limits and current customer account balances.
b. the accounting department supervisor independently reconciles the accounts receivable subsidiary ledger to the accounts receivable control account monthly.
c. the accounting department supervisor controls the mailing of monthly statements to customers and investigates any differences reported by customers.
d. the billing department supervisor matches prenumbered shipping documents with entries in the sales journal.