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: Radiology
Which of the following doesn't form the right side of the mediastinal shadow? 
Select and explain. 
A. Superior venacava, B. Right innominate vessels, C. Right border of atrium, D. Right ventricle
D: Right ventricle
Answer: D: Right ventricle 
Explanation: Right ventricle forms the anterior border of hea.