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: Dental
[{'content': '4th state of matter is \nSelect and explain. \nA. Solid, B. Liquid, C. Gas, D. Colloid', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]