Which statement about device mobility is true?

Which statement about device mobility is true?

A.
Where local route groups are used, there is no need to conjure device mobility groups or phone device CSSs as long as phone line CSSs are used.

B.
When local route groups are used, you must configure device mobility groups and phone device CSSs.

C.
When the device mobility group at the home device pool and roaming device pool are not the same, the phone will keep the home region.

D.
When device mobility groups at the home device pool and roaming device pool are the same, the phone will keep the home MRGL setting.