This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: mycology, Subject name: Microbiology
A farmer has an ulcer on a leg with indurated margin and multiple sinuses with discharging black granules. The likely diagnosis is 
Select and explain. 
A. Mycetoma, B. Scrofuloderma, C. Lupus vulgaris, D. Actinomycosis
A: Mycetoma
Answer: A: Mycetoma 
Explanation: Actinomycotic mycetoma - white to yellow granules and filaments are thin. Mycotic mycetoma - black granules and filaments are stout. Ref: Textbook of Microbiology, Ananthanarayan and Paniker; 9th edition