Final answer:
The correct answer is option 5) lower collective pitch and apply aft cyclic.
Step-by-step explanation:
The student's question pertains to the actions required to execute a quick stop in a helicopter. When a pilot wants to perform a quick stop, the correct maneuver is to lower the collective pitch and apply aft cyclic.
This action decreases the lift generated by the rotor system and shifts the thrust vector to decelerate the helicopter. It is crucial that these controls are adjusted smoothly and carefully to maintain control and prevent a hard landing or tail strike.