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 person after 6 hr. of consuming rice pudding in restaurant develops vomiting. True statements regarding food poisoning- 
Select and explain. 
A. Caused by staphylococcus aureus, B. Preformed toxin, C. Caused by vibrio parahaemolyticus, D. Heat labile toxin
B: Preformed toxin
Answer: B: Preformed toxin 
Explanation: Ans. is 'b' i.e., Preformed toxin . Vomiting within 6 hours of ingestion of rice suggests the diagnosis of emetic type of food poisoning caused by B. cereus. . It caused by preformed heat stable enterotoxin. . In emetic form, B. cereus is not found in large numbers in fecal specimens. Therefore food sample is more useful.