This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pericardium & Heart, Subject name: Anatomy
[{'content': 'Eustachian valve is seen in - \nSelect and explain. \nA. Eustachian tube opening at nasopharyngeal end, B. Eustachian tube opening in tympanic cavity, C. IVC opening in right atrium, D. Coronary sinus opening in right atrium', 'role': 'user'}, {'content': "Answer: C \nExplanation: 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 valve/Thebesian valve (functional valve)", 'role': 'assistant'}]