This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
[{'content': 'Reason for small casting \nSelect and explain. \nA. Compensation for shrinkage of alloy is not done., B. Incomplete burn out of wax pattern., C. Low casting pressure., D. All of the above.', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Reasons for ROUNDED MARGINS: It occurs due to incomplete burn out of wax pattern.\nReasons for SMALL CASTING: It occurs if compensation for shrinkage of alloy is not done.', 'role': 'assistant'}]