<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 56-year-old man comes to the physician because of intermittent retrosternal chest pain. Physical examination shows no abnormalities. Endoscopy shows salmon pink mucosa extending 5 cm proximal to the gastroesophageal junction. Biopsy specimens from the distal esophagus show nonciliated columnar epithelium with numerous goblet cells. Which of the following is the most likely cause of this patients condition?? A: Neoplastic proliferation of esophageal epithelium, B: Esophageal exposure to gastric acid, C: Atopic inflammation of the esophagus, D: Hypermotile esophageal contractions, E: Fungal infection of the lower esophagus,  <response>: This is a clinical vignette describing a 56-year-old man with intermittent chest pain. Endoscopy showed findings consistent with Barretts esophagus - salmon pink mucosa proximal to the GE junction and biopsy showing intestinal metaplasia. The most likely cause of Barretts esophagus is chronic gastroesophageal reflux disease GERD leading to esophageal exposure to gastric acid. This causes metaplastic changes in the normal squamous epithelium of the distal esophagus to a columnar epithelium more resistant to acid exposure.Choice A is incorrect because neoplastic changes would not explain the endoscopic or histologic findings described. Choice C is incorrect because an atopic process would not lead to metaplastic changes. Choice D is incorrect because esophageal hypermotility would not cause the changes seen. Choice E is incorrect because a fungal infection would not lead to intestinal metaplasia.Therefore, the most likely cause of this patients Barretts esophagus is choice B - esophageal exposure to gastric acid.B: Esophageal exposure to gastric acid 