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: Pathology
[{'content': 'A person experiences throbbing pain at night. It is due to \nSelect and explain. \nA. Acute pulpal degeneration, B. Acute periodontal abscess, C. Chronic pulpitis, D. Cellulitis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]