In the bowel obstruction lectures an abdominal series is a supine abdominal X-ray, an erect abdominal X-ray and an upright chest X-ray: one chest film plus two views of the abdomen. No option says this exactly. B is the only option with a single chest film and two views of the abdominopelvic region; C (2 chest views) and D (lateral decubitus) do not match the series. A could also be read as "chest + abdominopelvic film", but it leaves out the two abdominal views.