This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Pediatrics
Most common type of atrial septal defect is ___________ 
Select and explain. 
A. Ostium primum, B. Ostium secondum, C. Endocardial cushion defect, D. Endocardial hyperophy
B: Ostium secondum
Answer: B: Ostium secondum 
Explanation: Most common type of ASD is ostium secundum. Ref : Ghai essential of pediatrics, eighth edition, p.no:413