If an auditor performs analytical procedures on rent expense and finds that rent expense has increased 50%, he or she is most likely to perform which of the following additional procedures?

a. Test rent cutoff to determine if all rent has been recorded.

b. Vouch rent payments to underlying documents to determine that all vouchers have receiving reports.

c. Vouch larger items in rent expense in a search for unrecorded finance leases.

d. Perform tests of controls to ensure that all rent transactions are authorized.