What protects the nail bed from bacterial invasions?

The cuticle serves an important protective function for the nail bed. It is a layer of dead skin that overlaps the nail plate at the base of the nail. By forming this barrier, the cuticle helps to seal off the area where the nail grows from potential contaminants, such as bacteria and fungi, which could lead to infections if they penetrate the delicate nail bed beneath.

While nail polish and base coat can offer some level of protection to the nails themselves, they do not provide direct protection to the nail bed. Similarly, a nail hardener is formulated to strengthen the nails but does not function in the same protective capacity as the cuticle does. Thus, the cuticle is specifically designed to safeguard the nail bed from invading microorganisms, making it the correct answer.