<prompt> True statement about ductus arteriosus is:It undergoes anatomic closure within 24 hours of birthForms the ligamentum venosum in later lifeIt is induced to close by high levels of prostaglandinsMay cause a machinery murmur by its patency.  <response>: d. May cause a machinery murmur by its patency.Ref: Nelsons 20e p 497, Ghai 8e p 413Closure 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. 