After completing the testing of controls over cash receipts and sales adjustments, the auditor assesses the level of control risk to be higher than expected. How would this affect the auditor's substantive audit work on accounts receivable?

More work would need to be performed to ensure that the allowance for doubtful debts is fairly stated.

Less work would need to be performed on following up non-responses from the auditor's debtors' circularisation.

The auditor may consider changing the date of the debtors' circularisation from one month before the year-end, to the actual year-end date.

More analytical review tests could be performed on debtors as a substitute for other substantive tests.