You are answering a USMLE-style medical question. Question: A 58-year-old woman presents to the office for routine follow-up. She recently underwent routine screening for bone density due to a history of hypothyroidism. She also has a history of gastroesophageal reflux disease (GERD) that is being treated with a proton-pump inhibitor (PPI) and more recently with a histamine2 receptor antagonist (H2RA), hypertension being treated with a thiazide diuretic, depression being treated with lithium, and hormone replacement therapy. Her results meet the criteria for osteopenia, with a T-score of -1.6. She is concerned about progressive bone loss and the risk of fractures. Which of the following medication classes should be discontinued? Options: A) Proton-pump inhibitors B) Thiazide diuretics C) Lithium D) Estrogen Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.