Anatomical obliteration of ductus aeriosus occurs at:

Complete anatomical obliteration by proliferation of the intima is thought to take 1-3 months.Patent ductus aeriosus (PDA)Failure of a child's DA to close after bih results in a condition called patent ductus aeriosus and the generation of a left-to-right shunt.If left uncorrected, patency leads to pulmonary hypeension and possibly congestive hea failure and cardiac arrhythmias.Prostaglandins are responsible for maintaining the ductus aeriosus.Closure may be induced with a drug class known as NSAIDs such as indomethacin or ibuprofen because these drugs inhibit prostaglandin synthesis.A patent ductus aeriosus affects around 40% of infants with Down syndrome (DS).Changes in circulation after bihThe ductus aeriosus is occluded, so that all blood from the right ventricle now goes to the lungs, where it is oxygenated.Initial closure of the DA is caused by contraction of the muscle in the vessel wallLater in 1-3 months intima proliferation obliterates the lumenSo looking at the choices, 'D' option seems the best answer