Correct Option: B

Tricuspid valve is present between right auricle and right ventricle. It has 3 membranous flaps to check the flow of blood in reverse direction. Sinus venosus and right auricle are guarded by sinu-atrial value. The opening of left auricle and left ventricle is guarded by bicuspid valve. The opening of ventricle and aorta is guarded by semilunar valves.