How does international air law address the nationality of aircraft?

International air law addresses the nationality of aircraft primarily through the principles established by the Chicago Convention and its subsequent protocols. The correct answer emphasizes that for an aircraft to have a nationality, it must be registered in a specific country. This registration process is vital because it formally associates the aircraft with the jurisdiction of that country, providing it with legal recognition and protection under that nation's laws and international treaties.

National registration also means that the aircraft is subject to the regulations and oversight of the registering country, including safety and maintenance standards. This ensures that each aircraft is accountable to a recognized legal entity, which is crucial for international operations and cross-border flights.

The other options presented do not accurately reflect the principles of international air law. The requirement for registration ensures that nationality can be legally attributed to the aircraft, thereby making option B the correct interpretation of how international air law governs the nationality of aircraft.