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
Compared to resin base the main disadvantage of a metallic denture base in distal extension situation is that, metal bases: 
Select and explain. 
A. Are difficult to keep clean, B. Transfer thermal changes quickly to mucosa, C. Cannot be relined in event of ridge resorption, D. Are subjected to distortion and breakage
C: Cannot be relined in event of ridge resorption
Answer: C: Cannot be relined in event of ridge resorption 
Explanation: None