In which part of the gastrointestinal tract do ulcers typically form in ulcerative colitis?

Ulcerative colitis is a type of inflammatory bowel disease (IBD) that specifically affects the colon and rectum. In this condition, inflammation occurs in the innermost lining of the colon, leading to the formation of ulcers, which can result in symptoms such as abdominal pain, diarrhea, and rectal bleeding. The disease is characterized by continuous lesions starting from the rectum and potentially extending throughout the colon, making it distinct from Crohn's disease, which can affect any part of the gastrointestinal tract.

Other options involve different parts of the gastrointestinal system that are not affected in ulcerative colitis. The stomach is associated with conditions such as gastritis or peptic ulcers. The small intestine is more commonly involved in diseases like Crohn’s disease. The pancreas, while vital for digestive functions, does not develop ulcers related to ulcerative colitis. Therefore, the correct answer focuses on the specific area of the gastrointestinal tract where ulcerative colitis primarily causes damage and ulceration: the colon and rectum.