How is a disk repartitioned when it is added to a diskset?

How is a disk repartitioned when it is added to a diskset?

A.
The entire drive is mapped to slice 0.

B.
A small portion of the drive is mapped to slice 3 and the remainder to slice 4.

C.
A small portion of the drive is mapped to slice 7 or 6 and the remainder to slice 0.

D.
The drive is automatically converted to an EFI label regardless of the size of the drive.