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: Surgery
Stress ulcers is caused by all of the following except? 
Select and explain. 
A. Bums, B. Cortisol therapy, C. Penicillin therapy, D. Pulmonary insufficiency
C: Penicillin therapy
Answer: C: Penicillin therapy 
Explanation: None