The following are multiple choice questions (with answers) about medical knowledge.   **Question:** Which of the following is the common factor for the initiation of both dental caries and periodontal disease   (A) bacterial plaque   (B) lactic acid   (C) calculus   (D) no common factor
['(A) bacterial plaque <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) bacterial plaque \n (B) lactic acid \n (C) calculus \n (D) no common factor <> possible answers', '  Which of the following is the common factor for the initiation of both dental caries and periodontal disease <> context@']