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: Physiology
[{'content': 'The hormone using an enzyme receptor for its action: \nSelect and explain. \nA. Insulin, B. Steroid, C. Oestrogen, D. Thyroxine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Insulin', 'role': 'assistant'}]