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
3 weeks after insertion of distal extension partial denture, the patient reports to the dental clinic with complaint of sensitivity to chewing pressure. The most probable reason would be: 
Select and explain. 
A. Improper occlusion, B. Abrasion of tooth by clasp, C. Wearing off the cement base, D. Passive retentive arm
A: Improper occlusion
Answer: A: Improper occlusion 
Explanation: None