2. Which structures in the diagram above connects the umbilical vein with the vena cava and connects the pulmonary artery with the aorta?
A: A, the ductus arteriosus; D the ductus venosus
B: B, the ductus arteriosus; D the ductus venosus
C: B, the ductus venosus; D the ductus arteriosus
D: A, the ductus venosus; D the ductus arteriosus