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: Medicine
[{'content': 'Earliest pathological change is X-ray in Ulcerative Colitis - \nSelect and explain. \nA. Loss of haustration, B. Aphthous ulcerattions, C. Mucosal granularity, D. Skip tensions', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]