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: Anatomy
Which of the following is a remnant of ductus aeriosus? 
Select and explain. 
A. Ligamentum aeriosum, B. Ligamentum teres, C. Both of the above, D. None of the above
A: Ligamentum aeriosum
Answer: A: Ligamentum aeriosum 
Explanation: On the right, when the distal pa of the sixth aoic arch and the fifth aoic arch disappear, the recurrent laryngeal nerve moves up and hooks around the right subclan aery. On the left, the nerve does not move up, since the distal pa of the sixth aoic arch persists as the ductus aeriosus, which later forms the ligamentum aeriosum Ref: Langman's embryology 11th edition Chapter 12.