In rendering cash count the auditor observed that one of the items being presented by the custodian of petty cash fund is a petty cash receipt voucher. The petty cash receipt voucher is for a return of a travel expense advance which was initially obtained from the petty cash fund and therefore being temporarily given back to the custodian. Which of the following follow-up audit procedures the auditor should perform in relation to the item noted?

a. The auditor should trace the petty cash receipt voucher to an adjusting entry at year end debiting petty cash fund and crediting advances to employees.

b. The auditor should trace the cash receipt voucher to the cancelled replenishment check.

c. The auditor should ensure that the petty cash receipt voucher is included among the valid cash items thus needing no adjustments at year-end.

d. The auditor should trace the return of expense advance to a subsequent deposit to the bank.