Company.com wishes to use HACMP on two IBM eServer pSeries servers. During the planning  session， it was decided to use the native serial ports s1 or s2 for a non-IP heartbeat network.  What should be done to ensure the serial network will function with HACMP heartbeats？（）  

• A、 Use either s1 or s2 port configured as a TTY interface with a NULL Modem cable.
• B、 Use the s2 serial port on each system configured as a TTY interface with a NULL modem cable.
• C、 Use the s1 port on each system configured as a TTY interface with a standard serial modemcable.
• D、 Verify with IBM support which native serial ports for the server model can be used for HACM  pheartbeats.