What is an IS auditor's BEST course of action if informed by a business unit's representatives that they are too busy to cooperate with a scheduled audit?

A. Reschedule the audit for a time more convenient to the business unit.
B. Begin the audit regardless and insist on cooperation from the business unit.
C. Notify the audit committee immediately and request they direct the audit begin on schedule.
D. Notify the chief audit executive who can negotiate with the head of the business unit.