The following are multiple choice questions (with answers) about medical knowledge.   **Question:** According to instrument formula given by G.V. Black, primary cutting edge angle should be:   (A) More than 50 degree   (B) More than 90 degree   (C) Less than 50 degree   (D) Less than 90 degree
['(A) More than 50 degree <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) More than 50 degree \n (B) More than 90 degree \n (C) Less than 50 degree \n (D) Less than 90 degree <> possible answers', '  According to instrument formula given by G.V. Black, primary cutting edge angle should be: <> context@']