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
Fracture or separation of porcelain and metal occurs due to: 
Select and explain. 
A. Increased thickness of porcelain, B. High occlusal contact, C. No metal conditioner used, D. Centric occlusal contact on metal-ceramic interface
D: Centric occlusal contact on metal-ceramic interface
Answer: D: Centric occlusal contact on metal-ceramic interface 
Explanation: None