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': 'Which Premolar has prominent transverse ridge \nSelect and explain. \nA. Lower 1st premolar, B. Upper 1st premolar, C. Both, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]