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': 'The pulp horn that is most likely to be exposed during cavity preparation on deciduous molars is \nSelect and explain. \nA. Mesiobuccal of first molar, B. Distobuccal of first molar, C. Mesiobuccal of second rnolar, D. Distobuccal of second molar', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]