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
Direction of placement of retentive pin holes should be: 
Select and explain. 
A. Perpendicular to external tooth surface, B. Parallel to external tooth surface, C. Parallel to other pins, D. Never beneath cusps to be restored
B: Parallel to external tooth surface
Answer: B: Parallel to external tooth surface 
Explanation: None