You are answering a USMLE-style medical question. Question: A previously healthy 27-year-old woman comes to the physician because of a 2-month history of depressed mood and fatigue. During this time, she has had a 5-kg (11-lb) weight gain. She reports trouble concentrating at her job as a preschool teacher and has missed work several times in recent weeks due to generalized fatigue. She has smoked 2 packs of cigarettes daily for 10 years and is actively trying to quit smoking. A drug is prescribed that will treat the patient's mood disturbance and support smoking cessation. This patient should be counseled about which of the following possible side effects of this drug? Options: A) Hypotension B) Urinary retention C) Tachycardia D) QTc prolongation Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.