The Profession of Arms is defined as:

The definition of the Profession of Arms as a vocation that serves under civilian authority to defend the Constitution underscores the military's role as an institution dedicated to upholding democratic values and ensuring the security of the nation. This concept reinforces the idea that military members are not only trained professionals but also part of a larger framework governed by civilian oversight, reflecting the foundational principle of civilian control of the military in a democracy.

This definition emphasizes the responsibilities that come with military service, including the commitment to act in the country's best interests while safeguarding the rights and freedoms guaranteed by the Constitution. It highlights the importance of adherence to ethical standards and the rule of law, which are essential for maintaining the trust and support of the civilian population.

The other choices do not encapsulate the complete essence of the Profession of Arms. While military tactics and personal honor are components of military life, they do not encompass the broader duty to the Constitution and civilian authority. Additionally, viewing the profession as an informal network diminishes the structured and purposeful nature of military service that is integral to its identity and function within society.