A 5-year-old girl is brought to the emergency department because of fever and severe abdominal pain. Acute appendicitis is diagnosed. In the examination room, she keeps her right hip flexed and resists active extension of the hip. The inflamed structure associated with these symptoms is most likely in contact with which of the following structures?
(A) Abdominal wall and the external oblique muscle
(B) Obturator internus muscle
(C) Psoas major muscle
(D) Quadratus lumborum muscle
(E) Transversus abdominis muscle
Correct answer : (C) Psoas major muscle