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 impoant 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: D i.e. Nodal gene The primitive streak is initiated and maintained by expression of nodal, a member of transforming growth factor /3 (TGF - 13) superfamilyQ.