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
A newborn baby has not passed meconium for 48 hours since bih. She has vomiting and distension of abdomen. The most appropriate investigation for evaluation would be 
Select and explain. 
A. Anorectal manometry, B. Rectal biopsy, C. Lower G1 contrast study, D. Trypsin estimation
C: Lower G1 contrast study
Answer: C: Lower G1 contrast study 
Explanation: C i.e. Lower GI contrast study Lower GI contrast study confirms the diagnosis & indicate the type of involvement, in cases of lower intestinal obstruction causing failure to pass meconium timelyQ.