Which warning indicates that a pilot may encounter a stall?

The stall warning system is specifically designed to alert pilots when the aircraft is approaching stall conditions. It typically employs visual and/or auditory signals to provide timely alerts, allowing pilots to take corrective actions, such as reducing the angle of attack or adding power to prevent an actual stall. This system is crucial during maneuvers that might lead to a stall, particularly at low speeds or high angles of attack.

The other choices do not directly relate to stall conditions. For instance, the landing gear warning indicates issues with the landing gear position or configuration during landing operations. The speed warning alerts pilots when they are nearing unsafe speeds, but it doesn't specifically signal stall conditions. Additionally, the turbulence warning provides information regarding potentially hazardous atmospheric conditions but does not indicate the aircraft's aerodynamics in relation to a stall.