19. Which of the following is an example of a preventative control?

a. A clerk is responsible for performing monthly bank reconciliations

b. An internal auditor recomputes batch totals and reconciles the input totals with the output totals

c. All employees must enter their codes using the numeric keypad prior to entry to a computer that houses highly sensitive programs and data files

d. An employee is required to follow procedures to rectify data entry errors and resubmit transactions for reprocessing