Which of the following MOST correctly describes a hot spare？（）

A.A drive assigned to an array that will only hold parity information used for rebuilding a failedarray drive.
B.An external hard drive to which all data is replicated to for recovery in the event of a failure.
C.A drive assigned to an array that will automatically be used to rebuild a failed array drive.
D.An extra drive purchased and stored in the parts cabinet to replace failed drives.