This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: JIPMER 2018, Subject name: Anatomy
The marked area develops from(in green colour) 
Select and explain. 
A. Septum Primum, B. Septum secundum, C. Ostium primum, D. Ostium secundum
A: Septum Primum
Answer: A: Septum Primum 
Explanation: The marked area is floor of fossa ovalis that developes from septum primum