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
Gap between true end of casting ring and wax pattern should be 
Select and explain. 
A. ¼ inch, B. ½ inch, C. 3/8 inch, D. one inch
A: ¼ inch
Answer: A: ¼ inch 
Explanation: None