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
Main disadvantage of PFM restoration is: 
Select and explain. 
A. Excessive tooth reduction, B. Porcelain is very brittle, C. PFM restoration is unaesthetic, D. All of the above
C: PFM restoration is unaesthetic
Answer: C: PFM restoration is unaesthetic 
Explanation: None