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
Most common cause of Cushing syndrome is 
Select and explain. 
A. Pituitary tumor, B. Ectopic ACTH producing tumor, C. Steroid supplementation, D. Adrenal tumor
C: Steroid supplementation
Answer: C: Steroid supplementation 
Explanation: Steroid supplementation is the most common cause of question syndrome.