Which condition exhibits paralysis on one vertical half of the body?

Hemiplegia is characterized by paralysis affecting one half of the body, typically resulting from a brain injury or stroke that affects one side of the brain. This condition can lead to significant impairment in motor functions on the side of the body opposite to the brain lesion, influencing the arm, leg, and facial muscles.

In contrast, quadriplegia refers to paralysis affecting all four limbs, which results from spinal cord injury or diseases impacting both the upper and lower extremities. Paraplegia denotes paralysis of the lower half of the body, particularly affecting the legs and lower trunk, generally due to injury at the thoracic, lumbar, or sacral levels of the spinal cord. Monoplegia involves paralysis of a single limb, which is a much more localized condition than hemiplegia.

Considering these definitions, hemiplegia’s specific focus on paralysis affecting one vertical half of the body makes it the correct choice.