A 70-year-old client with Parkinson's disease is receiving carbidopa/levodopa to help relieve the symptoms associated with the disease. Which finding will demonstrate the effectiveness of the medication.

A. Muscle control: Carbidopa/levodopa increases dopamine levels in the brain, which improves motor function, reducing tremors, rigidity, and bradykinesia. Improved muscle control shows the drug is effective. B. Mental state: While Parkinson’s can affect cognition, carbidopa/levodopa primarily targets motor symptoms, not mental function. C. Bladder control: Urinary problems may occur in Parkinson’s disease, but these are not the primary focus of carbidopa/levodopa therapy. D. Nutritional status: Nutrition can improve if motor control improves, but it is an indirect effect, not the main indicator of drug effectiveness.