Which component strikes the primer to ignite the cartridge?

The firing pin is the component responsible for striking the primer and igniting the cartridge. When the trigger is pulled on a firearm, the firing pin is forced forward, either by a spring or other mechanism, and makes contact with the primer located at the base of the cartridge. This impact crushes the primer, causing it to ignite and subsequently igniting the gunpowder inside the cartridge case. This chain reaction leads to the firing of the bullet.

The other components mentioned play different roles in the firearm's functionality. The receiver is the part of the firearm that houses the trigger mechanism and other components but does not directly initiate the ignition process. The breech refers to the part of the firearm where the cartridge is loaded; it also does not strike the primer. The bore is the internal part of the barrel through which the bullet travels after being fired, but it is not involved in initiating the firing process. Thus, the firing pin is crucial for the ignition of the cartridge, making it the correct answer.