<prompt> Ductus arteriosus closes in response to:Decrease in peripheral oxygen saturationIndomethacin therapyProstaglandin E1Increase in pulmonary vascular resistance  <response>: b. Indomethacin therapyRef: Nelsons 20e p 2197, Ghai 8e p 417Indomethacin, a Prostaglandin inhibitor is used in medical closure of Ductus arteriosus. 