This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
A patient presents with symptoms of hypoglycemia. Investigations reveal decreased blood glucose and increased insulin levels. The c-peptide assay is done which shows normal levels of C-peptide. The most likely diagnosis is - 
Select and explain. 
A. Insulinoma, B. Accidental sulfonylurea ingestion, C. Accidental exogenous insulin administration, D. Accidental metformin ingestion
C: Accidental exogenous insulin administration
Answer: C: Accidental exogenous insulin administration 
Explanation: None