A barium swallow is performed in a 44 year old female who has had difficulty swallowing for months. Radiographically, there is marked dilation of th esophagus with breaking in the distal poion where marked luminal narrowing exists. A biopsy of the lower esophagus shows prominent submucosal fibrosis with out much inflammation. Most likely cause is
Poal hypeension Iron deficiency Barrett esophagus CREST syndrome