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: Microbiology
[{'content': 'Most common organism, responsible for pseudomembranous colitis is: \nSelect and explain. \nA. Clostridium difficile, B. Clostridium botulism, C. Clostridium bifermentans, D. Clostridium histolyticum', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Pseudomembranous colitis refers to swelling or inflammation of the large intestine (colon) due to an overgrowth of Clostridium\xa0difficile (C. difficile) bacteria.\xa0\nThis infection is a common cause of diarrhea after antibiotic use.', 'role': 'assistant'}]