This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
Ductus aeriosus closes in response to ? 
Select and explain. 
A. Decrease in peripheral oxygen saturation, B. Indomethacin therapy, C. Prostaglandin El, D. Increase in pulmonary vascular resistance
B: Indomethacin therapy
Answer: B: Indomethacin therapy 
Explanation: Ans. is b' i.e., Indomethacin therapy