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: Medicine
[{'content': 'A 22 year old man had a Beef sandwich and Potato salad. He Vomited 2 hours after the meal. What is the probable diagnosis \nSelect and explain. \nA. S. aureus poisoning, B. Bacillus cereus poisoning, C. Clostridial poisonong, D. Helicobacter pylori poisoning', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Preformed toxin of S. aureus causes nausea within 1-6 hours of ingestion.\nCommon food associated are: Poultry, potato and egg salad.', 'role': 'assistant'}]