Final answer:
Benztropine may be to blame for the symptoms of urinary retention, mydriasis, and confusion in a patient with parkinsonism receiving multiple drugs.
Step-by-step explanation:
Out of the given options, Benztropine may be to blame for the symptoms of urinary retention, mydriasis, and confusion in a patient receiving multiple drugs for parkinsonism. Benztropine is an anticholinergic drug commonly used to treat parkinsonism, but it can cause side effects such as urinary retention, dilated pupils (mydriasis), and confusion.