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: Pediatrics
X–ray detect congenital anorectal malformation at – 
Select and explain. 
A. Immediately after birth, B. 24–48 hours, C. 48–72 hours, D. After 72 hours
B: 24–48 hours
Answer: B: 24–48 hours 
Explanation: An X-ray film of the abdomen is obtained 12-24 hours after birth, with baby being kept in an inverted position.