<prompt> Eustachian valve is seen in -Eustachian tube opening at nasopharyngeal endEustachian tube opening in tympanic cavityIVC opening in right atriumCoronary sinus opening in right atrium  <response>: Ans. is c i.e., IVC opening in right atrium o Opening of IVC in right atrium is guarded by - Eustachian valve rudimentary valve. o Opening of coronary sinus in right atrium is guarded by - Semilunar valveThebesian valve functional valve 