A data center has had a power outage. Which of the following should the administrator do FIRST once the power is restored？ （）

• A、 Identify which systems are the most critical and bring them up by level of importance.
• B、 Retrieve the latest backup tapes for immediate system restore using the GFS rotation.
• C、 Identify the least critical systems and then power those systems on first.
• D、 Determine the cause of the power outage and install UPS systems to prevent its reoccurrence.