You are answering a USMLE-style medical question. Question: A 46-year-old woman comes to the physician because of severe muscle and joint pain for 5 months. The pain varies in location and intensity. She also has joint stiffness in the morning and reports fatigue throughout the day that she attributes to not sleeping well. She reports a tingling sensation in her lower limbs. Her bowel habits are unchanged but she often feels bloated. She has primary hypertension and occasional migraine headaches. She does not smoke or consume alcohol. Her medications include propranolol and sumatriptan. She appears healthy. Examination shows symmetric muscular tenderness at the base of the neck, over the shoulders, and in the lumbosacral area. Strength and deep tendon reflexes are normal. Laboratory studies show: Hemoglobin 14.3 g/dL Leukocyte count 9300/mm3 Platelet count 230,000/mm3 Mean corpuscular volume 85 μm3 Erythrocyte sedimentation rate 12 mm/h Serum Glucose 92 mg/dL Creatinine 0.6 mg/dL TSH 3.1 μU/mL Urinalysis is within normal limits. Which of the following is the most appropriate therapy for this patient?" Options: A) Temazepam B) Vitamin B12 C) Amitriptyline D) Methotrexate " Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.