Answer:
D. Parkinson disease
Explanation:
Karl is having difficulty sitting upright and controlling his hands and movements. Among the given options for diseases corresponding to this symptom:
amyotrophic lateral sclerosis : causes weakness of muscles and loss of control of muscles.
multiple sclerosis : causes breakdown of signal transmission between brain and rest of the body.
Alzheimer disease : causes loss of memory and cognition
Parkinsons disease : causes difficulty in balancing the body and limb movement.
So among the given options Parkinsons disease is the most relevant neurological disorder corresponding the symptoms exhibited by Karl.