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: Anatomy
Pulmonary veins develops from: 
Select and explain. 
A. 6th aoic arch, B. Primitive left atrium, C. Left common cardinal vein, D. Left vitelline vein
B: Primitive left atrium
Answer: B: Primitive left atrium 
Explanation: Development of pulmonary veinsAt 27-29 days' gestation, the primitive pulmonary vein appears as an endothelial out-pouching from either the posterior superior left atrial wall or from the central pa of the sinus venosus proximal to the primordial lung venous plexus.Connection between the primitive pulmonary vein and pulmonary venous plexus occurs by 30 days' gestation.The common pulmonary vein enlarges and incorporates into the left atrium, and, normally, the pulmonary venous pa of the splanchnic plexus gradually loses its connection with the cardinal and umbilicovitelline veins.