The following are multiple choice questions (with answers) about medical knowledge.   **Question:** Incidence of extra canal in mandibular 1st molar is seen in   (A) 10%   (B) 20%   (C) 30%   (D) 40%
['(C) 30% <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) 10% \n (B) 20% \n (C) 30% \n (D) 40% <> possible answers', '  Incidence of extra canal in mandibular 1st molar is seen in <> context@']