Who are authorized persons able to carry a weapon onboard an aircraft?

The correct choice encompasses all of the listed roles, as each category includes individuals who may be permitted to carry a weapon onboard an aircraft under specific regulations and circumstances.

Flight attendants, especially those who have undergone specific training, can be authorized to carry a firearm as part of the Federal Flight Deck Officer (FFDO) program in the United States. This program allows trained crew members to have access to firearms to enhance security on passenger flights.

Law enforcement officers, such as police officers and Secret Service agents, are often allowed to carry weapons when traveling on duty. Their presence on flights serves to enhance security and can be crucial in emergency situations, given their law enforcement training.

Similarly, agents of the FBI and Postal Inspectors also have the authority to carry weapons while on duty, as they are federal law enforcement officers equipped to handle threats and enforce laws. Their training and authority provide an added layer of security for airline operations.

Therefore, by recognizing that all of these professionals have specific training and legal authorization related to the safety and security of air travel, it's clear that the correct answer includes all categories listed. This helps ensure a comprehensive understanding of who may be authorized to carry weapons onboard an aircraft, emphasizing the importance of regulated measures for aviation security.