Answer:
The correct answer is Morula stage.
Explanation:
Morula is the solid ball of cells formed by fertilized ovum and later forms blastula stage in the embryonic stage. This solid ball of the mass consists of 10 to 30 cells.
It is the final stage before the formation of the blastocoel, a fluid-filled cavity. It is the initial embryonic stage where mammalian cells fate decided to become either internal or external.
Thus, the correct answer is Morula stage.