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: Anaesthesia
During a surgery a patient developed muscle rigidity, increased hea rate and hypercarbia. Emergence of malignant hypehermia is suspected. The agent which precipitates this condition most commonly is: 
Select and explain. 
A. Succinyl choline, B. Dantrolene sodium, C. Gallamine, D. Pancuronium
A: Succinyl choline
Answer: A: Succinyl choline 
Explanation: Malignant hypehermia (MH) is commonly triggered by the administration of anesthetic agents; the commonest trigger is the depolarizing muscle relaxant succinylcholine alone or in conjunction with a volatile agent such as halothane. The earliest signs of MH during anesthesia are succinylcholine-induced masseter muscle rigidity (MMR) or other muscle rigidity, tachycardia, and hypercarbia (due to increased CO2 production). Hypehermia may be a late sign, but when it occurs, core temperature can rise as much as 1degC every 5 min. The treatment of choice is intravenous dantrolene. Drugs known to trigger malignant hypehermia: Inhaled general anesthetics Ether Halothane Methoxyflurane Enflurane Isoflurane Desflurane Sevoflurane Nondepolarizing muscle relaxants Succinylcholine Ref: Butterwoh IV J.F., Butterwoh IV J.F., Mackey D.C., Wasnick J.D., Mackey D.C., Wasnick J.D. (2013). Chapter 11. Neuromuscular Blocking Agents. In J.F. Butterwoh IV, J.F. Butterwoh IV, D.C. Mackey, J.D. Wasnick, D.C. Mackey, J.D. Wasnick (Eds), Morgan & Mikhail's Clinical Anesthesiology, 5e.Ether