Which of the following best describes a partial paralysis that affects a single limb?

The term that best describes partial paralysis affecting a single limb is "Monoplegia." Monoplegia refers specifically to the paralysis or weakness of one limb, which is consistent with the description in the question.

In contrast, hemiparesis involves weakness on one side of the body, typically affecting a limb on both the left and right sides, but not focusing on a single limb. Paresis is a general term for weakness, which could refer to any area of the body without specification to a limb. Quadriplegia refers to paralysis that affects all four limbs, meaning both arms and both legs are impacted, which is distinctly different from the paralysis of just one limb.

Therefore, understanding the prefix "mono-" in monoplegia indicates the focus on single-limb impairment, making this the most appropriate choice among the options provided.