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: Pathology
Bell's palsy is triggered by 
Select and explain. 
A. Exposure to Cold, B. Tooth extraction, C. Local and systemic infection, D. Any of the above
D: Any of the above
Answer: D: Any of the above 
Explanation: None