This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Which of the following can cause toxic megacolon in 36 year old lady? 
Select and explain. 
A. Amoebic colitis, B. IBS, C. Ulcerative colitis, D. Viral diarrhea
C: Ulcerative colitis
Answer: C: Ulcerative colitis 
Explanation: The hallmarks of toxic megacolon (toxic colitis), a potentially lethal condition, are nonobstructive colonic dilatation larger than 6cm and signs of systemic toxicity. The impoant etiologies of toxic megacolon include the following inflammatory causes: Ulcerative colitis Crohn colitis Pseudomembranous colitis The complication of toxic megacolon is perforation, even in the absence of colonic dilatation.