While explaining to a customer the fault tolerant benefits of x445 they ask what happens if they implement memory mirroring and a DIMM fails in the SMP expansion module.  Which of the following is the most appropriate response？（）

• A、The DIMM is taken off line， and fault tolerance is available on the other DIMMs only.
• B、The memory bank is taken offline and rebuilt with the online hot spare and then brought back on line.
• C、The memory bank containing the failed DIMM is taken off line， and the system is no longer fault tolerant until replaced.
• D、The DIMM is taken offline， and the online hot spare is initiated and the system remains fault tolerant.