During landing, what must be reduced safely below drag?

In the context of landing an aircraft, reducing thrust is crucial to manage the airplane's speed effectively as it approaches the runway. When the aircraft is descending for landing, maintaining the correct amount of thrust helps to control the rate of descent while ensuring that the aircraft remains stable and within safe operating parameters.

Too much thrust can lead to an increased airspeed, which may result in higher drag if not managed properly. By reducing thrust appropriately, pilots can achieve a safe approach speed, which is essential for a controlled landing. It's important to balance thrust with lift and drag to ensure a smooth transition to landing without excess speed that could complicate the landing phase.

The other aspects—weight, lift, and altitude—are also critical during landing but do not directly align as closely with the necessity to reduce something that contributes to drag. While weight affects performance and lift is necessary for safe flight, managing thrust directly correlates with controlling airspeed and drag during the landing approach.