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': 'Modiolus at the corner of mouth is formed by all of the following muscles except \nSelect and explain. \nA. Triangularis, B. Buccinator, C. Masseter, D. Orbicularis oris', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]