This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Small & Large Intestine, Subject name: Surgery
Which muscle is irritated by retrocecal appendicitis? 
Select and explain. 
A. Psoas, B. Obturator, C. Gluteus maximus, D. Quadratus
A: Psoas
Answer: A: Psoas 
Explanation: Ans. (a) PsoasRef: Bailey and Love 27th edition, Page 1303On hyperextension of hip by putting psoas muscle into action -- retrocecal appendicitis pain is exhibited.