The umbilical vein is connected with the vena cava through ductus venosus (structure B).
The Pulmonary artery is connected with the aorta through the ductus arteriosus (structure D)
Explanation:
The diagram depicts the mother and fetal circulation. Oxygenated blood enters the fetus through the umbilical vein. While some of this flow is diverted towards the developing liver vessels, the majority flows directly into the inferior vena cava, bypassing the liver by means of a transient fetal vessel called the ductus venosus.
In the normal postnatal circulation all of the blood coming from the pulmonary artery flows towards the lungs. In the fetus, however, a significant fraction of this blood is shunted into the Aorta instead through another transient fetal vessel known as the ductus arteriosus.
