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
Which of the following has important role in initiation and maintenance of primitive streak - 
Select and explain. 
A. FGF - 8, B. BMP - 4, C. EGRF, D. Nodal gene
D: Nodal gene
Answer: D: Nodal gene 
Explanation: None