You are answering a USMLE-style medical question. Question: A 62-year-old man is brought to the physician by his wife because of difficulties walking for the past year. He has had multiple falls over the past 4 months. Over the past 6 months, he has had progressive urinary urgency and now wears an adult diaper as is not always able to control the urge to void. His appetite has also decreased in this time period. He used to drive, but his wife convinced him to stop after she noticed that he was becoming increasingly inattentive while driving. He has type 2 diabetes mellitus and hypertension. Current medications include ramipril and metformin. His temperature is 37.1C (98.8F), pulse is 90/min and blood pressure is 132/88 mm Hg. Examination shows a broad-based gait with slow and short steps. Neurologic examination shows no focal findings. On mental status examination, he is oriented to person and place but not to time. Attention and concentration are impaired. He recalls only one of three objects after 5 minutes. Which of the following is the most appropriate therapy for this patient's symptoms? Options: A) Ventricular shunting B) Acetazolamide therapy C) Temporal lobectomy D) Donepezil therapy Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.