This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pathology
Which of the following is earliest sign of ulcerative colitis on double contrast barium enema (DCBE) study? 
Select and explain. 
A. Fine Mucosal granularity, B. Loss of haustrations, C. 'Collar-button' ulcers, D. Lead pipe colon
A: Fine Mucosal granularity
Answer: A: Fine Mucosal granularity 
Explanation: .