The following are multiple choice questions (with answers) about medical knowledge.   **Question:** Phosphate bonded investment should be completely carbon free, otherwise:   (A) Investment chips off when molten metal enters the mold space   (B) Black castings   (C) Carbon makes the casting brittle   (D) Smooth casting
['(C) Carbon makes the casting brittle <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) Investment chips off when molten metal enters the mold space \n (B) Black castings \n (C) Carbon makes the casting brittle \n (D) Smooth casting <> possible answers', '  Phosphate bonded investment should be completely carbon free, otherwise: <> context@']