Which logical drives are reserved for the Dell EMC Unity operating system?

A.
Drives 0 – 3 on 12-drive and 25-drive DPE models

B.
Drives 0 – 3 on only a 12-drive DPE model
Drives 1 – 4 on only a 25-drive DPE model

C.
Drives 0 – 3 on only a 25-drive DPE model
Drives 1 – 4 on only a 12-drive DPE model

D.
Drives 1 – 4 on 12-drive and 25-drive DPE models