What are the components of a bullet?

The correct answer highlights the essential components that make up a bullet, which are crucial for understanding ammunition and the mechanics of firearms. A bullet is the projectile that is fired from a gun, but it does not exist in isolation. The casing holds everything together, providing a structure for the cartridge. Inside the casing, gunpowder serves as the propellant, generating gas and pressure when ignited, enabling the bullet to exit the barrel at high speed. The primer is a small but critical component; it ignites the gunpowder when struck by the firing pin of a firearm, leading to the discharge of the bullet.

In contrast, other options present combinations that either mislabel or misrepresent the components. For instance, referring to "bullet" and "casing" separately without recognizing that the bullet is the complete assembly which includes the projectile can lead to confusion. Additionally, terms like "slug" and "wad" are specific to certain types of ammunition (like shotgun shells) and do not apply universally in the context of a standard bullet, which comprises a casing, powder, primer, and the bullet or projectile itself. This comprehensive understanding is essential for proper firearm operation and safety.