A 56-year-old woman with poorly controlled type 2 diabetes mellitus presents with a 3-week history of weight loss and perioral stomatitis. Vital signs: BP 138/82, HR 92, RR 18, Temp 37.2°C, SpO2 98%. She has a migratory erythematous rash with blistering and crusting over the groin and extremities. Laboratory studies reveal fasting glucose 285 mg/dL, elevated glucagon level of 850 pg/mL, and normal albumin. She denies diarrhea. Which diagnosis best explains these findings?

1. A)Prolactinoma
2. B)VIPoma
3. C)GlucagonomaGABARITO
4. D)Somatostatinoma
5. E)Insulinoma