This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Definitive treatment of hypermagnesemia is? 
Select and explain. 
A. Calcium gluconate, B. IV fluids, C. Hemodialysis, D. Exchange resins
C: Hemodialysis
Answer: C: Hemodialysis 
Explanation: Hemodialysis REF: Harrison's 17th ed chapter 346 HYPERMAGNESEMIA: TREATMENT Successful treatment of hypermagnesemia generally involves identifying and interrupting the source of magnesium and employing measures to increase magnesium clearance from the BCF. Use of magnesium-free cathaics or enemas may be helpful in clearing ingested magnesium from the gastrointestinal tract. Vigorous IV hydration should be attempted, if appropriate. Hemodialysis is effective and may be required in patients with significant renal insufficiency. Calcium, administered IV in doses of 100-200 mg over 1-2 h, has been repoed to provide temporary improvement in signs and symptoms of hypermagnesemia.