This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
[{'content': 'In the adult hea, floor of fossa ovalis represents: \nSelect and explain. \nA. Septum intermedium, B. Septum primum, C. Septum spurium, D. Septum secundum', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B: Septum primumFossa ovalis and anulus ovalis lie on the atrial septum, which separates the right atrium from the left atrium.The fossa ovalis is a shallow depression, which is the site of the foramen ovale in the fetus.The anulus ovalis forms the upper margin of the fossa.The floor of the fossa represents the persistent septum primum of the hea of the embryo, and the anulus is formed from the lower edge of the septum secundum', 'role': 'assistant'}]