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: Medicine
The structure marked with arrow is: 
Select and explain. 
A. Coronary artery, B. Pulmonary artery, C. Arch of aorta, D. Pulmonary vein
A: Coronary artery
Answer: A: Coronary artery 
Explanation: None