Final answer:
Alcohol and drug abuse is the most frequent reason for a nurse's license to be suspended or revoked, as it can lead to serious patient care mistakes and is treated with seriousness by state nursing boards.
Step-by-step explanation:
The most frequent reason for a nurse's license to be suspended or revoked is alcohol and drug abuse. Nursing is a profession that demands high levels of responsibility and integrity, and impairment due to substance abuse can lead to serious mistakes and lapses in patient care. State boards of nursing are invested in protecting the public from unsafe practices and thus treat substance abuse by healthcare professionals with great seriousness. While criminal activity, mental impairment, and fraud are also serious offenses that can lead to disciplinary actions, statistics indicate that substance abuse is a leading factor resulting in disciplinary actions against nurses.