What types of matters are addressed under the four sources of military law?

The correct choice focuses on the key aspects of military law, which primarily address discipline and conduct within the military. Military law encompasses a wide range of regulations and standards that govern the behavior of service members, ensuring good order and discipline within the armed forces. This includes the Uniform Code of Military Justice (UCMJ), which outlines offenses and corresponding military judicial processes.

Maintaining discipline is crucial in a military environment, where cohesion and order can significantly impact operational effectiveness. Therefore, military law is specifically designed to deal with the unique circumstances that service members face, emphasizing accountability and ethical conduct under the distinct structure of military duty.

The other options do not capture the essence of military law's focus. Civilian complaints, while potentially relevant to military personnel, do not form the core of military law. Similarly, while international relations might intersect with military operations, they fall outside the purview of military law as it pertains to the governance of service member behavior. Financial regulations are also significant but are typically managed through different frameworks and do not directly relate to the disciplinary and conduct standards that military law addresses.