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
Infection of all the following structures can be cause of Psoas abscess except- 
Select and explain. 
A. Vertebrae, B. Appendix, C. Hip joint, D. Ribs
D: Ribs
Answer: D: Ribs 
Explanation: None