Which option describes the reason that transcoding resources are added in Cisco Unified Communications Manager?

A.
to enable transcoding resources in a Cisco Unified Communications Manager server

B.
to enable Cisco Unified Communications Manager to select the optimal single codec for end-to-end calls

C.
to enable transcoding resources in Cisco IP Phones

D.
to provide transcoding resources in Cisco IOS gateways to Cisco Unified Communications Manager