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
To prevent porosity in dental porcelain it should be
baked: 
Select and explain. 
A. In presence of air, B. In vacuum, C. For long period, D. Under pressure
B: In vacuum
Answer: B: In vacuum 
Explanation: To prevent porosity in dental porcelain, it should be baked in vacuum.