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 cook is habitual of nose picking while cooking. His clients are at risk for food poisoning with: 
Select and explain. 
A. Clostridia difficle, B. Staph aureus, C. Vibrio cholerae, D. Bacillus cereus
B: Staph aureus
Answer: B: Staph aureus 
Explanation: Ans. is b. Staph aureus