The correct response identifies that "shots" travel through the barrel of a shotgun. In the context of firearms, a shotgun is designed to fire shots that are made up of multiple small pellets, commonly referred to as shot. This is distinct from rifles, which fire a single bullet. When the shotgun is fired, the gunpowder ignites, propelling the shot out of the barrel in a spread pattern, which is ideal for hunting birds and small game.
To clarify, cartridges and shells technically refer to the complete unit that includes the shot, gunpowder, and casing, and while they do go through the firearm in the sense of being chambered, they are not what exits the barrel. Bullets typically refer to a single projectile used in rifles and pistols, not the multiple projectiles fired from a shotgun. Therefore, the emphasis on "shots" accurately describes what is expelled from the shotgun barrel upon firing.