Answer:
Gastrulation.
Step-by-step explanation:
The embryonic development occurs through the different developmental stages like cleavage, morula, blastula and so on. The formation of the germ layers occur in the gastrulation period.
The primitive streak is the structure that develops during the early stages of the gastrulation. As the embryo becomes asymmetric., the cells moves from their initial position and leads to the formation of primitive streak in the gastrulation phase.
Thus, the correct answer is option (C).