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': 'Purulent exudation from the gingival sulci is an indication of: \nSelect and explain. \nA. Deep pockets, B. Severe periodontal attachment loss, C. Nature of the inflammatory changes in the pocket wall, D. Shallow pockets', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]