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: Radiology
First radiological sign of ulcerative colitis is: 
Select and explain. 
A. Pseudopolyp formation, B. Loss of haustrations, C. Tubular colon, D. Increased retrorectal space
B: Loss of haustrations
Answer: B: Loss of haustrations 
Explanation: Ans. Loss of haustrations