This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S., Subject name: Pediatrics
True statement about ductus arteriosus is: 
Select and explain. 
A. It undergoes anatomic closure within 24 hours of birth, B. Forms the ligamentum venosum in later life, C. It is induced to close by high levels of prostaglandins, D. May cause a machinery murmur by its patency.
D: May cause a machinery murmur by its patency.
Answer: D: May cause a machinery murmur by its patency. 
Explanation: d. May cause a machinery murmur by its patency.(Ref: Nelson's 20/e p 497, Ghai 8/e p 413)Closure of ductus arteriosusPhysiological closure: occurs almost immediately after birth by contraction of muscular wall, mediated by bradykininAnatomic closure: occurs by proliferation of intima in 10-21 days; After obliteration, it forms ligamentum arteriosum. Note: Murmur due to PDA is classically referred to as a continuous machinery murmur.