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
Myospasm that is involuntary continuous contraction of a muscle due to overstretching which is already strained
because of sustained mouth opening during RCT is 
Select and explain. 
A. Charley horse, B. Ercess expand, C. Muscle tear, D. Hardy stretch
A: Charley horse
Answer: A: Charley horse 
Explanation: None