Which definition of Caller Input on Cisco Unity Connection is true?

Which definition of Caller Input on Cisco Unity Connection is true?
A. It defines actions that Cisco Unity Connection takes in response to phone keys that are pressed by callers during a call handler greeting.
B. It defines actions that Cisco Unity Connection takes in response to a preconfigured call handler.
C. Transfers all incoming calls to the Opening Greeting call handler.
D. Plays a brief goodbye message and then hangs up.