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
Tissue conditioners are not used for long as they 
Select and explain. 
A. Harden in mouth, B. Are expensive, C. Are difficult to fabricate, D. Cause ridge resorption
A: Harden in mouth
Answer: A: Harden in mouth 
Explanation: None