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: Surgery
Regarding Schatzki's ring the true statement is: 
Select and explain. 
A. Has skeletal muscle, B. Located at upper esophagus, C. Located at lower esophagus, D. Contain all layers of esophagus
C: Located at lower esophagus
Answer: C: Located at lower esophagus 
Explanation: Schatzki's ring is a lower esophageal mucosal ring May result from GERD Asymptomatic 10% Cause dysphagia Ref: Bailey & Love, 25th Edition, Pages 1041