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': 'Which of the following function as second messengers: \nSelect and explain. \nA. CAMP, B. DAG, C. IP3, D. All', 'role': 'user'}, {'content': 'Answer: D \nExplanation: All Correct', 'role': 'assistant'}]