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
Buccal coil spring used to regain space between 1st premolar and 1st molar causes following common post treatment complication: 
Select and explain. 
A. Pain, B. Gingival irritation, C. Tendency of 1st premolar to rotate, D. Tendency of 1st premolar to intrude
C: Tendency of 1st premolar to rotate
Answer: C: Tendency of 1st premolar to rotate 
Explanation: None