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
Onychophagia is 
Select and explain. 
A. Finger biting habit, B. Nail biting habit, C. Mouth breathing habit, D. None of the above
B: Nail biting habit
Answer: B: Nail biting habit 
Explanation: None