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
Radiological signs of crohn's disease – 
Select and explain. 
A. String sign of Kantor, B. Pipestem appearance, C. Pseudopolyp, D. Backwash ileitis
A: String sign of Kantor
Answer: A: String sign of Kantor 
Explanation: String sign of Kantor is seen in Crohn's disease.
Other three options (Pipestem appearance, pseudopolyp, Backwash ileitis) are features of UC.