<prompt> All the following openings in the right atrium are guarded by valve except -Superior vena cavaInferior vena cavaCoronary sinusAtrioventricular opening  <response>: Valves on different openings to Right atrium- Inferior vena cava- Rudimentary semilunar valve- Eustachian valve- Coronary sinus- Incomplete semicircular valve- Thebesian valve- AV opening- Tricuspid valve 