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
[{'content': 'Staph. aureus causes vomiting in 16-18 hours. The mechanism of action is \nSelect and explain. \nA. Stimulation of cy AMP, B. Vagal stimulation, C. Stimulation of cy GMP, D. Acts through ganglioside GM receptor', 'role': 'user'}, {'content': 'Answer: B \nExplanation: "The mechanism by which the staphylococcus aureus causes vomiting is uncertain but may involve direct neural stimulation of the autonomic nervous system rather than a local effect on G.I.T mucosa".', 'role': 'assistant'}]