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: Pathology
S100 is a marker for: 
Select and explain. 
A. Melanoma, B. Schwannoma, C. Histiocytoma, D. Hemangioma
A: Melanoma
Answer: A: Melanoma 
Explanation: Melanoma