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
The threshold dose of fluoride that requires immediate emergency treatment and hospitalization in acute fluoride toxicity is: 
Select and explain. 
A. 4mg, B. 5mg, C. 6mg, D. 7mg
B: 5mg
Answer: B: 5mg 
Explanation: None