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
Mc fayden reaction seen with which organism ? 
Select and explain. 
A. Clostridium perfringens, B. Clostridium botulinum, C. Bacillus cereus, D. Bacillus anthracis
D: Bacillus anthracis
Answer: D: Bacillus anthracis 
Explanation: Ans. is `d' i.e., Bacillus antracis Mc Fadvean's reaction When blood films containing anthrax bacilli are stained with polychrome methylene blue for a few seconds and examined under microscope, an amorphous purplish material is noticed around bacilli. This represents the capsular material and is characteristic of the anthrax bacillus.