While executing a Cluster Test Plan， the administrators realize that they will need to email the  Operations and network on-call staff in the event of a network outage.  What can be done to alert the on-call staff of network failures？（）   

• A、 Customize clstat to send a mail message.
• B、 Customize an Event Notification method.
• C、 Customize an Error Notification method.
• D、 Customize clinfo to send an SNMP trap.