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
Mercury intoxication in dental office mainly results from: 
Select and explain. 
A. Direct contact with the mercury, B. Inhalation of mercury vapours, C. Ingestion of mercury, D. None of the above
B: Inhalation of mercury vapours
Answer: B: Inhalation of mercury vapours 
Explanation: None