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: Pharmacology
[{'content': "'Lock and Key model' of enzyme action was proposed by \nSelect and explain. \nA. Emil Fisher, B. Daniel Koshland, C. Lenor Michaelis, D. Maud Menten", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Lock and key hypothesis By emil Fischer Active site is rigid Substrate has complimentary shape Demerits: 1. Rigid active site in reversible reaction. 2. Stabilization of transition state Ref: G n G 13th ed.', 'role': 'assistant'}]