An operator just completed a repair to a disk subsystem that contains a disk heartbeat. Before returning the system back into production mode， there is a requirement to verify the disk heartbeat is functioning.  How should the operator determine if the disk heartbeat network functioning？（）   

• A、 Use the clinfo command to monitor the disk heartbeat
• B、 Use the mail command to check for messages form HACMP
• C、 Use the dhbread command to verify the disk heartbeat link
• D、 Use the clstat command to verify the appropriate network connections are available