This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
[{'content': "Which of the following is true regarding anthrax \nSelect and explain. \nA. M' Fadyean reaction shows capsule, B. Human are usually resistant to infection, C. Less than 100 spores can cause pulmonary infection, D. Gram stain shows organism with bulging spores", 'role': 'user'}, {'content': "Answer: A \nExplanation: M' Fadyean's reaction: When blood films containing anthrax bacilli are stained with polychrome methylene blue for a few seconds and examined under a Microscope, amorphous purplish material is noticed around the bacilli. This represents the capsular material and is characteristic of the anthrax bacilli. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 251", 'role': 'assistant'}]