Final answer:
The most appropriate response by the nurse would be to inform the client that dry mouth and dizziness are common side effects of the prescribed medications for Parkinson's disease.
Step-by-step explanation:
Benztropine mesylate (Cogentin) and carbidopa-levodopa (Sinemet) are prescribed for a client with Parkinson's disease. The client's complaint of a "dry mouth" and "dizziness" are common side effects of these medications. Both drugs work on the nervous system to address symptoms of Parkinson's disease.