When investigating variant behavior, which of the following is NOT necessary to determine?

When investigating variant behavior, determining whether the subject is under 18 years old is not necessary in the context of making assessments about behaviors or mental health conditions. The focus in investigations typically revolves around understanding the individual’s current mental state, any necessary interventions, and the appropriate legal frameworks that apply, particularly for those who might be mentally ill or require protective custody.

Choices that involve the subject's mental health diagnosis, the need for protective custody, or the application of specific laws related to mentally ill individuals are critical because they directly impact the response to the subject's behavior and the legal obligations of law enforcement and mental health professionals. Each of these options necessitates careful evaluation to ensure that proper procedures are followed and that the subject's rights and safety are prioritized.

In contrast, while age can be a factor in certain situations—particularly in the realms of juvenile justice and care—it does not fundamentally alter the investigative approach to variant behaviors as much as the other elements do. Hence, the inquiry into the age of the subject is less relevant in the specific context of determining necessary actions based on variant behavior or mental health issues.