What mechanism governs control of the E-Series storage premium features? (Choose the best answer.)

What mechanism governs control of the E-Series storage premium features? (Choose the best answer.)
A . simple password system
B . special USB flash drive that must be inserted into the controllers
C . small toggle switches on the controller boards inside the system
D . key file obtained from vendor and passed to system via SANtricity
E . online database requiring the controllers to access the internet to activate features

Answer: D