You are answering a USMLE-style medical question. Question: A 68-year-old man presents to the emergency department with confusion. The patient lives in a nursing home and has Alzheimer dementia at baseline. His nurse noticed that he was more confused than usual and was somnolent for the past 12 hours. The patient’s nurse also noticed that he was soiling his diapers more frequently with copious amounts of urine. The patient has lost 15 pounds since his last physician appointment 3 weeks ago. Laboratory values are ordered as seen below. Serum: Na+: 139 mEq/L Cl-: 100 mEq/L K+: 4.3 mEq/L HCO3-: 25 mEq/L BUN: 20 mg/dL Glucose: 99 mg/dL Creatinine: 1.1 mg/dL Ca2+: 12.2 mg/dL PTH: 8 pg/mL The patient is referred to another physician for a more thorough workup including laboratory work and CT imaging. Which of the following is the best long-term prophylaxis for the cause of this patient’s acute symptoms? Options: A) Alendronate B) Calcitonin C) IV fluids D) Teriparatide Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.