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': 'A characteristic feature of lingual surface of the mandibular first premolar is: \nSelect and explain. \nA. Rudimentary lingual cusp, B. Mesial marginal ridge, C. Mesiolingual developmental groove, D. Lingual triangular ridge', 'role': 'user'}, {'content': 'Answer: C \nExplanation: A characteristic of the lingual surface of the mandibular first premolar is the mesiolingual developmental groove. This groove acts as a line of demarcation between the mesiobuccal lobe and the lingual lobe and extends into the mesial fossa of the occlusal surface.', 'role': 'assistant'}]