input: The following are multiple choice questions (with answers) about medical knowledge.   **Question:** The porosity formed due to simultaneous nucleation of solid grains and gas bubbles at the first moment that metal freezes at the mold walls is called:   (A) Pinhole porosity   (B) Gas inclusion porosity   (C) Micro porosity   (D) Subsurface porosity.
output: ['(D) Subsurface porosity. <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) Pinhole porosity  (B) Gas inclusion porosity  (C) Micro porosity  (D) Subsurface porosity. <> possible answers', '  The porosity formed due to simultaneous nucleation of solid grains and gas bubbles at the first moment that metal freezes at the mold walls is called: <> context']