What is an example of a malfunction for the M4 Rifle?

A failure to eject is classified as a malfunction of the M4 Rifle because it refers to a situation in which the spent cartridge does not exit the chamber after a round is fired, preventing the weapon from cycling properly and getting ready to chamber the next round. This malfunction can lead to operational delays and may require remedial action from the user, such as clearing the rifle and inspecting the chamber and extractor for any obstructions or issues.

Conversely, the other options do not represent malfunctions of the rifle itself. A failure to sight pertains more to aiming accuracy rather than a mechanical issue with the weapon's function. A failure to aim describes a user error rather than a fault with the firearm. Finally, a failure to secure is not specific to the weapon's firing mechanism and relates to weapon handling or storage practices rather than a mechanical malfunction. Thus, a failure to eject directly impacts the rifle's operational capabilities and is a clear example of a malfunction.