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': 'Calculus is the: \nSelect and explain. \nA. Governing factor., B. Contributing factor., C. Etiological factor., D. Primary factor.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Calculus does not directly irritate the gingiva but it provides a fixed nidus for the continued accumulation of plaque and holds it against gingiva and thus acts as a contributing factor.', 'role': 'assistant'}]