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': 'The predominant cell type in gingival crevicular fluid is the : \nSelect and explain. \nA. Mast cell, B. Plasma cell, C. Macrophage, D. Polymorphonuclear leukocyte', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]