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
String sign is seen in – 
Select and explain. 
A. Crohns disease, B. TB of the ileocaecal region, C. Idiopathic hyperophic pyloric stenosis, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: String sign → Congenital hypertrophic pyloric stenosis, Ileocecal tuberculosis.
String sign of Kantor → Crohn's disease
String of bead sign → Small bowel obstruction