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
Right side of mediastinum shadow is not formed by: 
Select and explain. 
A. Superior venacava, B. Right innominates, C. Right atrium, D. Right ventricle
D: Right ventricle
Answer: D: Right ventricle 
Explanation: D i.e. Right ventricle