R1 as an NTP server must have:
* NTP authentication enabled
* NTP packets sourced from Interface loopback 0
* NTP stratum 2
* NTP packets only permitted to client IP 209.165.200.225
How should R1 be configured?

A. ntp authenticate
ntp authentication-key 2 sha1 CISCO123
ntp source Loopback0
ntp access-group server-only 10
ntp master 2
!
access-list 10 permit udp host 209.165.200.225 any eq 123
B. ntp authenticate
ntp authentication-key 2 md5 CISCO123
ntp interface Loopback0
ntp access-group server-only 10
ntp stratum 2
!
access-list 10 permit 209.165.200.225
C. ntp authenticate
ntp authentication-key 2 md5 CISCO123
ntp source Loopback0
ntp access-group server-only 10
ntp master 2
!
access-list 10 permit 209.165.200.225
D. ntp authenticate
ntp authentication-key 2 md5 CISCO123
ntp source Loopback0
ntp access-group server-only 10
ntp stratum 2
!
access-list 10 permit udp host 209.165.200.225 any eq 123