The following are multiple choice questions (with answers) about medical knowledge.   **Question:** Pickling:   (A) Is accomplished by soaking the casting in baking soda   (B) Causes porosity in gold   (C) Removes surface oxides from gold castings   (D) Remove investment from gold casting
['(C) Removes surface oxides from gold castings <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) Is accomplished by soaking the casting in baking soda \n (B) Causes porosity in gold \n (C) Removes surface oxides from gold castings \n (D) Remove investment from gold casting <> possible answers', '  Pickling: <> context@']