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 mesial marginal is a developmental groove present on \nSelect and explain. \nA. Maxillary 1st Premolar, B. Maxillary 2nd Premolar, C. Mandibular 1st Premolar, D. Mandibular 2nd Premolar', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]