You are answering a USMLE-style medical question. Question: A 54-year-old man comes to the physician for a routine health maintenance examination. He was diagnosed with type 2 diabetes mellitus 1 year ago. His only medication is metformin. His serum glucose is 186 mg/dL and his hemoglobin A1c is 7.6%. The physician prescribes an additional antidiabetic drug and counsels the patient on its delayed onset of action. At a follow-up appointment 4 weeks later, the patient reports that his home blood glucose readings have improved. He also mentions that he has had a weight gain of 4 kg (8.8 lb). The patient has most likely been treated with which of the following drugs? Options: A) Empagliflozin B) Liraglutide C) Rosiglitazone D) Glyburide Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.