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.
['(D) Subsurface porosity. <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) Pinhole porosity \n (B) Gas inclusion porosity \n (C) Micro porosity \n (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@']