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
Intermittent dysphagia is caused by -a) Strictureb) Reflux esophagitisc) Achalasia cardiad) Pharyngeal diverticulme) Diffuse esophageal spasm 
Select and explain. 
A. ab, B. bc, C. cd, D. de
D: de
Answer: D: de 
Explanation: None