Which of the following is MOST commonly affected in U.C.-

Ans. is 'b' i.e., RectumThe most common site of involvement in Ulcerative colitis is the rectum.Ulcerative colitis (involvement is limited to the colon)o Ulcerative colitis typically starts in the rectum and may progress with continuous lesions (no skip lesions) in a retrograde manner to involve the entire colon (Pancolitis)."UC is a mucosal disease that usually involves the rectum and extends proximally to involve all or part of the colon. About 40 to 50% of patients have disease limited to the rectum and rectosigmoid. 30 to 40% have disease extending beyond the sigmoid but not involving the whole colon, and 20% have a total colitis. Proximal spread occurs in continuity, without areas of uninvolved mucosa ".