What must be verified by the DZSO before a drop occurs?

The DZSO, or Drop Zone Safety Officer, plays a crucial role in ensuring that a parachute drop operation is conducted safely and effectively. Before a drop occurs, it is essential for the DZSO to verify multiple factors that contribute to the overall safety and success of the operation.

Verifying weather conditions is critical because adverse weather, such as strong winds or poor visibility, can significantly affect the safety of jumpers upon descent and landing. The DZSO must ensure that weather conditions are suitable for a safe drop.

Additionally, personnel readiness is another key aspect to be checked. This involves confirming that all jumpers are properly equipped, trained, and mentally prepared for the jump. Any issues with personnel readiness can lead to dangerous situations during the drop.

Lastly, aircraft availability is equally important. The DZSO must ensure that the aircraft planned for the operation is ready, operational, and able to transport the jumpers safely to the drop altitude. Any issues with the aircraft could lead to postponement or cancellation of the drop, potentially putting the mission at risk.

Therefore, comprehensive verification of weather conditions, personnel readiness, and aircraft availability is necessary to mitigate risks and ensure a successful jump operation, making "All of the above" the correct response.