This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteria, Subject name: Microbiology
Medusa head colonies on nutrient agar is seen in - 
Select and explain. 
A. Pneumococcus, B. Legionella, C. Brucella, D. Anthrax
D: Anthrax
Answer: D: Anthrax 
Explanation: Ans. is 'd' i.e., Anthrax * Important characteristics of B. anthracis : 'Inverted fir tree' appearance, 'frosted glass' appearance, medusahead colony, string of pearl's reaction, M' Fadyean's reaction.