Final answer:
The least severe classification of criminal law is an infraction, which is typically punished by a fine, and it is less severe than misdemeanors, felonies, and is not a part of civil law as torts are.
Step-by-step explanation:
The least severe classification of criminal law is d) Infraction. An infraction is a minor violation, often punishable by a fine rather than jail time, such as a traffic ticket. On the other hand, a misdemeanor is more severe than an infraction and can carry penalties including jail time, fines, and community service. A felony is even more serious, with the possibility of more than one year of incarceration, and a tort is not a classification of criminal law, but rather a wrongful act leading to civil legal liability. Therefore, in the context of criminal law, an infraction would be the least severe classification.