What is contained within the casing of a bullet?

The casing of a bullet, often referred to as a cartridge case, contains several critical components that work together to facilitate the firing process. The correct answer highlights that within the casing, there is the bullet, the powder, and the primer.

The bullet is the projectile that is expelled from the firearm when the gun is fired. The powder, specifically gunpowder, acts as the propellant; when ignited by the primer, it creates gas that builds up pressure behind the bullet, launching it out of the barrel. The primer serves as the ignition source — a small explosive charge that ignites the powder when struck by the firing pin.

Other options describe incomplete components of the cartridge. For instance, stating that only the powder is contained ignores the essential roles of both the bullet and primer. Similarly, options mentioning only two of the components leave out critical elements that are necessary for the firing of the round. Thus, understanding that the casing encompasses all three components — the bullet, powder, and primer — is fundamental for grasping how ammunition operates in firearms.