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 one of the following is not essential for primary impression: \nSelect and explain. \nA. Retention, B. Stability, C. Phonetics, D. Aesthetics', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]