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 of the following plaque is most harmful and causes spread of Inflammation to the connective tissue leading to bone destruction: \nSelect and explain. \nA. Subgingival epithelial attached, B. Subgingival unattached, C. Subgingival plaque, D. Supragingival plaque', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]