In which of the following situations would an auditor most likely use a reliance strategy?

a. The client has been slow to update its IT system to reflect changes in billing practices.

b. The auditor hired an IT specialist whose report to the auditor reveals that the specialist did not perform sufficient procedures to allow the auditor to properly assess the effect of the IT system on control risk.

c. A client receives sales orders, bills customers, and receives payment based only on information generated from its IT system-no paper trail is generated.

d. The auditor has been unable to ascertain whether all changes to a cli- ent's IT system were properly authorized.