Which of the following are the four forces affecting flight?

The four forces affecting flight are lift, weight, thrust, and drag. Each of these forces plays a crucial role in determining the movement and stability of an aircraft.

Lift is the upward force generated as air flows over the wings, allowing the aircraft to rise off the ground. Weight is the force due to gravity acting on the aircraft, pulling it downward. Thrust is the forward force produced by the aircraft's engines, propelling it through the air. Drag is the resistance force that opposes thrust, typically caused by friction and pressure differences as the aircraft moves through the atmosphere.

Collectively, these four forces interact to control the aircraft's flight path, allowing pilots to maneuver, climb, descend, and maintain level flight. The correct identification of these forces is fundamental in understanding basic aerodynamics and effective flight operations, making option A the comprehensive answer that accurately reflects the essential forces of flight.