This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anaesthesia, Subject name: Anaesthesia
Minimum alveolar concentration {MAC} of an anaesthetic agent means it produces lack of reflex response to skin incision in,--- of subjects - 
Select and explain. 
A. 25%, B. 50%, C. 75%, D. 100%
B: 50%
Answer: B: 50% 
Explanation: Minimum alveolar concentration is defined as the alveolar concentration of an inhaled anesthetic agent that prevents movement in 50% of patients in response to a standardized surgical stimulus. Low MAC - High potency MAC values of adult Halothane: 0.75 Sevoflurane: 2.0 Isoflurane: 1.2 Desflurane: 6.0 Enflurane: 1.7 Xenon: 70 N2O: 104 Ref: Miller's anesthesia 8th edition Ref: Morgan & Mikhail's clinical anesthesiology 6e