Which area prohibits all aircraft due to national security reasons?

The correct choice is indeed the prohibited area, which is specifically established to protect national security interests. These areas are designated by the Federal Aviation Administration (FAA) or other relevant authorities, and they restrict all aircraft from entering, regardless of the nature of their operation. The prohibition is often in place due to the presence of sensitive military operations, government installations, or other significant national security concerns.

In contrast, restricted areas allow for controlled activities, which may include military training or testing, but they can be accessed by aircraft with prior permission from the appropriate authorities. Class G airspace, being uncontrolled, does not have such restrictions and is open to all aircraft under specific conditions. Military Operations Areas (MOAs) are also designated for military use but do not prohibit civilian aircraft entirely; rather, they are areas where military training exercises occur, and civilian pilots are advised to exercise caution when flying through these regions. Thus, the distinction lies in the absolute prohibition that characterizes prohibited areas, ensuring total security for sensitive activities or locations.