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 immunoglobulin in sulcular fluid is: \nSelect and explain. \nA. Ig A, B. Ig G, C. Ig M, D. Ig E', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]