A 43-year-old woman presents with recurrent episodes of diaphoresis, tremor, and confusion that resolve after consuming juice. Vital signs show HR 102, BP 138/88, RR 16, temp 37°C. During a 72-hour supervised fast, plasma glucose drops to 42 mg/dL with inappropriately elevated insulin (18 mIU/L) and C-peptide (2.1 ng/mL). Liver function tests are normal. Which of the following is the most likely diagnosis?

1. A)Pheochromocytoma
2. B)Exogenous insulin administration
3. C)InsulinomaGABARITO
4. D)Sulfonylurea use
5. E)Addison disease