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: Unknown
In Barrett esophagus, esophageal lining is changed to: 
Select and explain. 
A. Squamous epithelium, B. Columnar epithelium, C. Pseudostratified epithelium, D. None of the above
B: Columnar epithelium
Answer: B: Columnar epithelium 
Explanation: Barrett esophagus is a metaplasia of the esophageal mucosa caused by the replacement of the squamous epithelium with columnar epithelium.