Which of the following must be included in the syslogd configuration file, so that ONLY kernel related messages with the priority crit are reported?

A and C are correct

The Selectors function are encoded as a facility, a period (“.”), and a level, with no intervening white-space. Both the facility and the level are case insensitive.

This syslogd(8) has a syntax extension to the original BSD source, that makes its use more intuitively. You may precede every priority with an equation sign (”=”) to specify only this single priority and not any of the above. You may also (both is valid, too) precede the priority with an exclamation mark (”!”) to ignore all that priorities, either exact this one or this and any higher priority. If you use both extensions than the exclamation mark must occur before the equation sign, just use it intuitively.