Which of the following control activities would best protect against the preparation of improper or inaccurate cash disbursements?
a. All checks must be signed by an officer designated by the board of directors.
b. All signed checks must be reviewed and compared with supporting documentation by the treasurer before mailing.
c. All checks must be sequentially numbered and accounted for by internal auditors.
d. All checks must be perforated or otherwise effectively canceled when they are returned with the bank statement.