What distinguishes muzzleloaders from other firearms?

Muzzleloaders are uniquely characterized by the fact that they are loaded from the end of the barrel, or muzzle, which is a defining feature that distinguishes them from other types of firearms. This loading method involves inserting a projectile and powder directly into the open end of the barrel before firing.

This is in contrast to many modern firearms, which are typically breech-loaded, meaning that ammunition is loaded through the rear of the barrel. Muzzleloaders also often have a different operating mechanism, requiring an ignition source such as a cap or a fuse, and they rely on traditional ammunition forms that include loose powder and a projectile, which further emphasizes their distinct nature.

While considerations about weight and ease of carrying can be subjective, and although special ammunition is indeed a factor in some cases, the primary and most definitive aspect is the loading method through the muzzle, making option C the correct choice.