Which type of paralysis involves the inability to move a single limb?

Monoplegia refers specifically to paralysis that affects a single limb, which is why this choice is correct. This type of paralysis can occur as a result of various conditions, including strokes or injuries, and it is characterized by weakness or complete loss of movement in just one arm or one leg.

In contrast, diplegia involves paralysis affecting symmetrical parts of the body, typically both arms or both legs, rather than a single limb. Paraplegia affects the lower half of the body, specifically both legs, resulting in loss of movement and sensation in those areas. Quadriplegia, also known as tetraplegia, results in paralysis of all four limbs, affecting both arms and both legs. Therefore, when considering the scope of paralysis to just one limb, monoplegia is distinctly the appropriate term.