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': 'Negative growth is a characteristic of: \nSelect and explain. \nA. Testis, B. Brain, C. Mandible, D. Thymus', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]