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: Surgery
A Neonate is brought with history of not having passed meconium on examination there is no anal opening but a dimple. Investigation of choice is - 
Select and explain. 
A. X-ray erect posture, B. X-ray supine posture, C. Gastrograffin study, D. Invertogram
D: Invertogram
Answer: D: Invertogram 
Explanation: • Anorectal malformations are associated with VACTERL abnormalities.