You are answering a USMLE-style medical question. Question: A 51-year-old man presents to his primary care provider for intermittent shaking of his hands. He reports that for the last several years he has noticed this "shaking" when he brushes his teeth and prepares a cup of coffee in the morning. The shaking then gradually improves over the course of the day. His past medical history is otherwise notable for hypertension and hyperlipidemia. His only home medication is pravastatin. The patient smokes half a pack per day of cigarettes and drinks 2-3 beers throughout the day. His family history is significant for Parkinson disease in his father. On physical exam, his blood pressure is 159/84, pulse is 74/min, and respirations are 12/min. He has a high frequency bilateral hand tremor elicited on finger-to-nose testing. His neurological exam is otherwise unremarkable. This patient should be started on which of the following medications? Options: A) Alprazolam B) Primidone C) Propranolol D) Trihexyphenidyl Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.