Image-first read: A target-like mass in the lumen with contrast feathering into a coiled-spring pattern is intussusception.
Intussusception is one bowel segment sliding into the one ahead of it, like collapsing a telescope. On a contrast enema this produces a filling defect with a meniscus or claw of contrast cupping its apex, and as contrast tracks between the inner and outer tubes it outlines stretched mucosal folds as a coiled spring. Clinically think infant, intermittent screaming and drawing-up of legs, and redcurrant-jelly stool; the plain film may show an empty right iliac fossa with a soft-tissue mass.
Eliminate the rest: An apple-core or napkin-ring stricture is colonic carcinoma. A coffee-bean shaped dilated loop rising out of the pelvis is sigmoid volvulus. Sac-like outpouchings with focal inflammation are diverticular. None of these is a telescoped target, so intussusception is the answer.
Ref: David Sutton, Textbook of Radiology and Imaging, 7th edition.