Which IOS command is used to define the authentication …

Which IOS command is used to define the authentication key for NTP?

A.
Switch(config)#ntp authentication-key 1 md5 C1sc0

B.
Switch(config)#ntp trusted-key 1

C.
Switch(config)#ntp source 192.168.0.1

D.
Switch(config)#ntp authenticate