This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Anaesthesia
Index of potency of general anesthesia 
Select and explain. 
A. Minimum alveolar concentration, B. Diffusion coefficient, C. Dead space concentration, D. Alveolar blood concentration
A: Minimum alveolar concentration
Answer: A: Minimum alveolar concentration 
Explanation: Minimal alveolar concentrationIt is the lowest concentration of the anaesthetic in pulmonary alveoli needed to produce immobility in response to a painful stimulus (surgical incision) in 50% individualsIt is the measure of potency of inhalation Gas.(Refer: Morgan and Mikhail's Clinical Anaesthesiology, 5th edition, pg no. 162 - 163)