Germinal layers are the result of
Implantation
Gastrulation
Cleavage
Trophoblast
Gastrulation is the process through which the presumptive areas of organ specific rudiments present on the surface of blastula move on their specific positions where these occur in the adult. Gastrulation results in setting apart of three primary Germinal layers, i.e., the Ectoderm, mesoderm, and endoderm.
Option b is the correct answer.