What does the main rotor blade assembly primarily do?

The main rotor blade assembly is crucial in the operation of rotary-wing aircraft, as it primarily generates both lift and thrust. Lift is produced as the rotating blades move through the air, creating a difference in pressure above and below the blades. This allows the helicopter to rise and achieve altitude. Additionally, the main rotor blades contribute to thrust by tilting the rotor disc, which propels the aircraft in the desired direction.

Whereas other choices focus on unrelated systems or functionalities, such as the auxiliary power unit, tail rotor mechanics, or flight navigation automation, these do not describe the primary role of the main rotor blade assembly. The essence of rotorcraft performance is driven by the lift and thrust generated by the rotor blades, making this the correct answer.