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
The right side of mediastinum shadow is not formed by: 
Select and explain. 
A. Superior vena cava, B. Right innominate vein, C. Right atrium, D. Right ventricle
D: Right ventricle
Answer: D: Right ventricle 
Explanation: Ans. Right ventricle