Final answer:
Treavor is required to register for military duty because it is his legal and civic duty under the Selective Service Act. This law requires all 18-year-old males to register, allowing them to be called upon for service if a draft is instituted. Such laws have historically been used to ensure a nation's defense readiness.
Step-by-step explanation:
Treavor is required to register for military duty primarily because it is his civic duty as stipulated by the law. In the United States, all males are legally mandated to register with the Selective Service upon turning 18, according to the Selective Service Act. This registration is a legal obligation that also serves as a form of preparation in case a military draft is instituted. Furthermore, while the US does not currently have mandatory military service, in the event of a draft, those registered could be called upon to serve. This mandate is made clear during the naturalization oath where individuals agree to serve when required by the law.
Military drafts have been employed during historical moments when nations perceived a threat to their security. For example, the Selective Service Act of 1940 was a proactive measure for ensuring the US had ample defense during World War II, requiring young men to register for the draft. The registration and potential conscription into the military are seen not just as a legal responsibility but as part of the wider civic engagement expected of citizens, which includes responsibilities like voting and jury duty.