Commonest sites of intraabdominal abscess :: (A) Subphrenic, (B) Paracolic, (C) Pelvis, (D) Retroperitoneal
Answer is C. The pelvis is the commonest site of intrabdominal abscess because of 2 reasons

because the vermiform appendix is often pelvic in position.
because the fallopian tubes are frequent sites of infection.