Answer- D. Toxic megacolonToxic megacolon is a serious life-threatening condition that can occur in patients with ulcerative colitis, Crohn'scolitis, and infectious colitides such as pseudomembranous colitisThis decompensation results in a necrotic thin-walled bowel in which pneumatosisa can often be seen radiographically.Diagnosis:Plain abdominal radiographs are critical for diagnosing toxic megacolon and for following its course.Transverse colon is usually the most dilated >6 cm on supine films.Mutiple air-fluid levels in the colon are common; normal colonic haustlal pattern is either absent or severely disturbed.