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: Skin
[{'content': 'Pyoderma gangrenosum is seen in : \nSelect and explain. \nA. Crohns disease, B. Diveuculosis, C. Ulcerative colitis, D. Ca. Colon', 'role': 'user'}, {'content': "Answer: C \nExplanation: C. i.e. Ulcerative colitis Pyoderma gangrenosum occurs in both ulcerative colitis & Crohn's diseaseQ. But - 50% of PG occurs in association with UC. And - 2% of active UC patients have PG and another 4% UC patients have erythema nodosum. The mean duration of chronic ulcerative colitis before the appearance of erythema nodosum & PG is 5 & 10 years respectively.", 'role': 'assistant'}]