<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 54-year-old woman presents to her primary care physician complaining of watery diarrhea for the last 3 weeks. She reports now having over 10 bowel movements per day. She denies abdominal pain or rash. A basic metabolic profile is notable for the following: Na: 127 mEqL; K 2.1 mEqL; Glucose 98 mgdL. Following additional work-up, octreotide was started with significant improvement in symptoms and laboratory values. Which of the following is the most likely diagnosis?? A: VIPoma, B: Glucagonoma, C: Somatostatinoma, D: Insulinoma, E: Gastrinoma,  <response>: This is a clinical case question involving a patient with chronic diarrhea. The key findings are watery diarrhea for 3 weeks, more than 10 bowel movements per day, no abdominal pain or rash, hyponatremia, hypokalemia, and improvement with octreotide treatment. The choices list various pancreatic neuroendocrine tumors NETs. Based on the chronic watery diarrhea, electrolyte abnormalities suggestive of a secretory diarrhea, and good response to octreotide, the most likely diagnosis is a VIPoma. VIPomas secrete vasoactive intestinal peptide VIP leading to large volumes of watery diarrhea, hypokalemia, and hyponatremia from fluid loss. Octreotide is a somatostatin analog that inhibits VIP secretion. The other tumor choices do not match the clinical presentation as closely.A: VIPoma 