Due to a weakness observed in a client's control over recording retirement of equipment, the auditor may decide to

a. Trace additions to the "other assets" account to search for equipment that is still on hand but no longer being used.

b. Select certain items of equipment from the accounting records and locate them in the plant.

c. Inspect certain items of equipment in the plant and trace those items to the accounting records.

d. Review the subsidiary ledger to ascertain whether depreciation was taken on each item of equipment during the year.