What helps prevent accidental discharge of the firearm when not in use?

The trigger guard is a crucial component of a firearm designed specifically to prevent accidental discharge when the firearm is not in use. It serves as a protective barrier around the trigger, ensuring that it cannot be inadvertently pulled by foreign objects or during handling. This feature significantly reduces the risk of an accidental shot being fired, which is essential for safe firearm storage and transportation.

In contrast, other parts of the firearm, such as the bore, forestock, and receiver, do not provide the same level of protection against unintended firing. The bore is the interior of the barrel where the bullet travels and does not contribute to safety when the firearm is not in use. The forestock is mainly for gripping the firearm and stabilizing aiming, and while it plays a role in control during use, it does not prevent accidental discharges. The receiver houses critical components of the firearm, but by itself, it does not provide a safeguard against accidental firing. Hence, the trigger guard is specifically designed to enhance safety and is the correct answer.