Which is an example of a criminal violation?

In most jurisdictions, it is illegal to serve alcohol to someone who is already intoxicated. Intoxicated people are more likely to engage in risky behaviors, such as driving under the influence or getting into fights.
The other options are not criminal violations. It is not illegal to serve alcohol to a guest who is taking medication, a pregnant woman, or a regular. However, it is important to be aware of the potential risks involved in serving alcohol to these groups.