Which two Cisco ISR series are needed to support a Cisco Services-Ready Engine to deploy services on demand?

Which two Cisco ISR series are needed to support a Cisco Services-Ready Engine to deploy
services on demand? (Choose two.)

A.
3900 Series

B.
2900 Series

C.
2800 Series

D.
800 Series

Explanation:
http://www.cisco.com/en/US/prod/collateral/modules/ps10598/data_sheet_c78-553913.html