In a repeating firearm, what component holds ammunition until it is ready to be fed into the chamber?

In a repeating firearm, the component that holds ammunition until it is ready to be fed into the chamber is the magazine. The magazine serves a critical role by storing multiple rounds of ammunition, allowing the shooter to fire several shots without having to manually reload after each shot. When the firearm is operated, the action of cycling (either by bolt or lever) causes a round to be taken from the magazine and fed into the chamber, ready to be fired.

The barrel, chamber, and stock serve different functions: the barrel directs the projectile, the chamber is where the ammunition is held before firing, and the stock provides support and stability for the shooter. Therefore, the magazine is specifically designed to prepare and supply ammunition to the firearm efficiently, making it the correct answer.