Refer to the exhibit. The ntp server 192.168.0.3 command has been configured on router 1 to make it an NTP client of router 2. Which command must be configured on router 2 so that it operates in server-only mode and relies only on its internal clock?

A. Router2(config)#ntp server 172.17.0.1
B. Router2(config)#ntp server 192.168.0.2
C. Router2(config)#ntp passive
D. Router2(config)#ntp master 4