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？（）
- AThe DIMM is taken off line， and fault tolerance is available on the other DIMMs only.
- BThe memory bank is taken offline and rebuilt with the online hot spare and then brought back on line.
- CThe memory bank containing the failed DIMM is taken off line， and the system is no longer fault tolerant until replaced.
- DThe DIMM is taken offline， and the online hot spare is initiated and the system remains fault tolerant.