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
Base of hea is formed by 
Select and explain. 
A. Rt. ventricle, B. LV, C. LV + RV, D. RA + LA
D: RA + LA
Answer: D: RA + LA 
Explanation: D i.e. RA + LA The base of hea forms its posterior surface. It is formed mainly by the left atriumQ and by small pa of right atriumQ.