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: Microbiology
A person working in an abattoir presented with a papule on hand, which turned in to an ulcer. Which will best help in diagnosis 
Select and explain. 
A. Polychrome Methylene blue, B. Carbol Fuschin, C. Acid Fast Stain, D. Calcoflour White
A: Polychrome Methylene blue
Answer: A: Polychrome Methylene blue 
Explanation: None