You are answering a USMLE-style medical question. Question: A 16-year-old patient presents to the physician’s office with an absence of menstruations. Her last period was 6 months ago. Since almost a year and a half ago, she intentionally restricted her diet at the expense of carbohydrates, exercised intensively, and lost 18.0 kg (39.7 lb). She had her menarche at the age of 12 and menstruated normally until last year. She is not sexually active. On physical examination, the vital signs include blood pressure 100/60 mm Hg, heart rate 55/min, respiratory rate 12/min, and temperature 35.9°C (96.6°F). Her weight is 55.0 kg (121.3 lb), and her height is 166 cm (5 ft 5 in). Physical examination reveals the good development of muscles and decreased adiposity. A bone scan shows decreased calcium mineral deposits. Which statement about this patient’s condition is correct? Options: A) This patient has insulin resistance B) Decreased adiposity contributes to hypoestrogenemia in this patient C) The patient is likely to have decreased blood estrogen concentration due to increased liver metabolism D) The patient should be checked for hyperthyroidism because such extensive lipolysis is likely to result from thyroid hyperfunction Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.