Which statements are true about the HP 3PAR StoreServ 7000? (Select two.)

A.
Within a column, there can be empty slots between drives.

B.
Columns of drives must be of the same drive type and rotational speed for HDDs.

C.
Drives must be added in identical pairs.

D.
The LFF enclosure cannot be mixed with the SFF enclosure on the same node pair,

E.
All columns have to contain the same number of drives.