<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A previously healthy 67-year-old man comes to the physician because of a history of recurrent right lower abdominal pain for the past 2 years. A CT scan shows a 1.2-cm 0.47-in mass located in the terminal ileum. He undergoes surgical removal of the mass. A photomicrograph of the resected specimen is shown. Cells from this tissue are most likely to stain positive for which of the following?? A: Desmin, B: Chromogranin A, C: Vimentin, D: Cytokeratin, E: Glial fibrillary acid protein,  <response>: This is a question about identifying the type of tumor based on a histological image. The description indicates a 1.2 cm mass was found in the terminal ileum of a 67 year old man, and a photomicrograph of the resected tissue is provided. Based on the location and patient demographics, the leading differential would be gastrointestinal stromal tumor GIST vs neuroendocrine tumor NET vs adenocarcinoma. GISTs are mesenchymal tumors that stain positive for CD117 and DOG1. NETs are neuroendocrine in origin and stain positive for chromogranin A and synaptophysin. Adenocarcinomas are epithelial in origin and stain positive for cytokeratins.B: Chromogranin A 