The following are multiple choice questions (with answers) about medical knowledge.   **Question:** Which is not present in porcelain:   (A) Silica   (B) Feldspar   (C) Calcium carbonate   (D) Amorphous material
['(D) Amorphous material <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) Silica \n (B) Feldspar \n (C) Calcium carbonate \n (D) Amorphous material <> possible answers', '  Which is not present in porcelain: <> context@']