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': 'Composition of Varnish is: \nSelect and explain. \nA. 10% copal resin+90%solvent, B. 90% copal resin+10%solvent, C. 50% copal resin+50% solvent, D. 39% copal resin+70%solvent', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]