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
"Sulfur granules" are a feature of: 
Select and explain. 
A. Clostridia, B. Actinomyces, C. Aspergillus, D. Nocardia
B: Actinomyces
Answer: B: Actinomyces 
Explanation: Actinomyce