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': 'Cyclic GMP is the second messenger of: \nSelect and explain. \nA. Growth Hormone, B. Follicle Stimulating Hormone (FSH), C. Insulin, D. Thyroxin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C i.e. Insulin', 'role': 'assistant'}]