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
A group of friends had a party together, After 4 hours, few of them had diarrhoea and vomiting. Organism responsible for food poisoning is : 
Select and explain. 
A. S-typhi, B. CL.perfringens, C. B.cereus, D. Camp. jejuni
C: B.cereus
Answer: C: B.cereus 
Explanation: Incubation period of food poisoning
1-6 hours - S.auerus and B.cereus
8-24 hours- clostridium