This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Systemic Bacteriology Pa 1 (Gram Positive Cocci, Gram Negative Cocci), Subject name: Microbiology
[{'content': 'Staph. aureus causes vomiting in 2 hours after eating contaminated milk product . The mechanism of action is - \nSelect and explain. \nA. Stimulation of C AMP, B. Vagal stimulation, C. Stimulation of C GMP, D. Acts through ganglioside GM receptor', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Option 1, 3 Increase in cyclic AMP/GMP-accumulation of sodium chloride in the intestinal lumen- Diarrhea. Option 2 Toxin Stimulates the vagus nerve and vomiting center of brain. Acts directly on the autonomic nervous system rather than on gastrointestinal mucosa. Option 4 Cholera toxin: binds to GM1 ganglioside receptors present on the intestinal epithelium', 'role': 'assistant'}]