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
Ligamentum arteriosum is a remnant of 
Select and explain. 
A. Ductur arteriosur, B. Ductur caroticus, C. Ductur venosus, D. None
A: Ductur arteriosur
Answer: A: Ductur arteriosur 
Explanation: None