What is the torch primarily used for during a flight?

The torch is primarily used during a flight to provide illumination during emergencies. In situations where cabin lights may not function effectively or when passengers need guidance to exit the aircraft, having a reliable source of light can help ensure safety and aid in evacuation procedures. This is critical as it enhances visibility in low-light conditions, helping both crew and passengers navigate the environment safely.

Other options, such as signaling other aircraft or providing regular light during the flight, do not align with the primary purpose of the torch, which is specifically for emergencies. While it might assist in reading safety cards, that is not its main function, making the emphasis on emergency illumination the best explanation for its use.