<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 31-year-old woman comes to the emergency department because of a 4-week history of worsening headache, nausea, and vomiting. The headache is worse at night. Fundoscopic examination shows swelling of the optic discs. A CT scan of the brain shows a heterogeneous, hyperintense, intraventricular mass. The patient undergoes surgical excision of the mass. Pathologic examination of the surgical specimen confirms that the tumor is of neuronal origin. The cells in this specimen are most likely to stain positive for which of the following immunohistochemical markers?? A: S-100, B: Desmin, C: Synaptophysin, D: Glial fibrillary acidic protein, E: Cytokeratin,  <response>: This is a clinical vignette describing a 31-year-old woman with worsening headaches, nausea, vomiting, and papilledema, along with imaging showing an intraventricular tumor. The tumor was surgically resected and found to be of neuronal origin on pathology. The question is asking which immunohistochemical marker the tumor cells are most likely to stain positive for. Based on the information provided, this is most likely a central nervous system tumor of neuronal origin. Choice A S-100 stains cells of neural crest origin and would not be expected to stain a neuronal tumor. Choice B Desmin stains muscle cells and would not apply here.Choice C Synaptophysin is an immunohistochemical marker for neurons and synapses, making it the most likely correct answer for a tumor of neuronal origin.Choice D GFAP stains astrocytes and would not be expected to stain a neuronal tumor. Choice E Cytokeratin stains epithelial tissues and would not apply to this CNS neuronal tumor.C: Synaptophysin 