This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thorax, Subject name: Anatomy
Coronary sinus is guarded by 
Select and explain. 
A. Crista terminalis, B. Thebesian valve, C. Mitral valve, D. Spiral valve
B: Thebesian valve
Answer: B: Thebesian valve 
Explanation: Opening of coronary sinus is guarded by thebesian valve. BD CHAURASIA'S HUMAN ANATOMY VOLUME 1. 6TH EDITION.Page no -255