A customer site is set up as follows:

Aggregation-layer Cisco Catalyst 6500 Series Switches
Redundant supervisors

The customer is deploying a new version of Cisco lOS.

Which supervisor redundancy mode or modes will allow an older version of Cisco lOS to be
maintained on a standby supervisor?

A.
RPR only

B.
SSOonly

C.
RPRandSSO

D.
RPRandRPR+