Which statement best describes the cause of a primary blast injury?

• A. The blast overpressure or wave from an explosion
• B. Shrapnel penetration
• C. Thermal burn
• D. Toxic inhalation

Answer: (A)

The main idea is that a primary blast injury comes from the rapid, high-pressure shock wave—the blast overpressure—produced by the explosion. This pressure spike travels through the body and can damage air-filled organs like the lungs and ears even when no debris hits you. Shrapnel, burns, and inhaled toxins cause injuries from separate mechanisms (secondary, thermal/quaternary effects), not from the initial pressure wave. So the best description of the cause is the blast overpressure wave from the explosion.