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
If during rubber dam application, you see the gingiva is protruding out of margins; what can be the cause for it? 
Select and explain. 
A. Holes on rubber dam placed too far from each other, B. Holes on rubber dam placed too close from each other, C. Gingival tissue around holes are oedematous, D. Rubber dam is too thin
B: Holes on rubber dam placed too close from each other
Answer: B: Holes on rubber dam placed too close from each other 
Explanation: Holes punched too close together - holes pull away from teeth causing leakage.
Holes punched too far apart- dam bunches up between teeth.
Holes position too low on the dam - dam covers patient's eyes or nose.
Holes position too high on dam - dam does not extend over upper lip.