For a stable patient with suspected Ogilvie's, the sources start with conservative management: bowel rest, NGT, IV fluids, stopping narcotics and correcting electrolytes. Neostigmine and colonoscopic decompression are kept for patients who do not respond. The sources also say a mechanical cause must be excluded first. The old bank's answer (gastrografin enema, C) does that, but the sources name CT, not a contrast enema, for this. So B is the best-supported answer and C is a defensible alternative.