This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: CVS Embryology, Subject name: Anatomy
The most common cardiac congenital malformations seen clinically is 
Select and explain. 
A. Persistent truncus aeriosus, B. Membranous VSD, C. Common ventricle, D. Foramen secundum defect
B: Membranous VSD
Answer: B: Membranous VSD 
Explanation: The most common of all cardiac congenital malformations seen clinically are membranous VSDs. The membranous interventricular septum forms by the proliferation and fusion of tissue from three different sources: Right bulbar ridge Left bulbar ridges Atrioventricular (AV) cushions. Because of this complex formation, the probability of defects is very high.