Which component is termed as the base of the barrel that holds the cartridge?

The chamber is the correct answer because it is the part of the firearm where the cartridge is seated before firing. It is specifically designed to hold the cartridge securely in position so the firing pin can strike the primer and ignite the powder within. The design of the chamber ensures that the cartridge is aligned correctly with the bore of the barrel for safe and accurate shooting.

In contrast, the magazine is the component that holds multiple cartridges and feeds them into the chamber as needed. The bolt is a mechanism that closes the breech of the firearm and can also help in feeding cartridges from the magazine into the chamber. The sight, on the other hand, is used for aiming and has no functional role in holding cartridges. Understanding the specific roles of these parts helps clarify why the chamber is correctly identified as the base of the barrel that holds the cartridge.