Answer:
(D). Ductus arteriosus.
Explanation:
Ductus arteriosus can be defined as a blood vessel that connects the main pulmonary artery and proximal descending aorta in developing fetus. It allows transfer of blood from the right ventricle to the non-functioning fluid filled lungs of fetus.
Ductus arteriosus is critical for fetal blood circulation. However, it does not play role in adult circulation.
Thus, the correct answer is option (D).
I
