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
Spore forming anaerobic gram positive bacilli ? 
Select and explain. 
A. Bacillus Anthracis, B. Clostridia, C. Corynebacterium, D. Peptostreptococcus
B: Clostridia
Answer: B: Clostridia 
Explanation: Ans. is 'b' i.e., Clostridia There are two medically impoant spore forming bacteria. Both of them are 'gram positive' `bacilli' :-Aerobic : BacillusAnaerobic (obligate anaerobes) : Clostridia.