At what age are men required to register for the Selective Service?

Men are required to register for the Selective Service at eighteen years old, which is a crucial civic responsibility in the United States. This requirement ensures that the government has a list of individuals eligible for potential military conscription in the event of a national emergency. The age of eighteen is significant because it marks the transition into adulthood, where individuals can vote, serve in the military, and make other important life decisions.

Other age options are not correct because sixteen is considered too young for such responsibilities, while twenty-one is generally associated with the legal drinking age and other legal adult privileges. Nineteen is also too late in the context of registration, as young men should be registered by the time they reach eighteen to ensure compliance with the law. Thus, registering at eighteen aligns with the legal framework and societal expectations for young adults.