<prompt> Which of the following events cause closure of ductus arteriosus in new bornCompression of thorax during deliveryCompression of pulmonary vessels during deliveryFall in pulmonary arterial pressureFall in systemic arterial pressure  <response>: Aeration of newborn lung causes rapid replacement of bronchial and alveolar fluid by air, with this compression of pulmonary vasculature is lowered which results in fall in pulmonary arterial blood pressure.Thus ductus arteriosus closes. 