The correct sequence is

The correct sequence is Zygote $\rightarrow$ Cleavage $\rightarrow$ Morula $\rightarrow$ Blastula $\rightarrow$ Gastrula. At about $30-36 \mathrm{hrs}$ after fertilisation, the zygote divides into smaller cells by a process called cleavage. It is division of cells. It results in a solid ball of cells, called morula. It is a 16 -celled stage. It forms blastula which is a 64 -celled stage. It contains a fluid-filled cavity called blastocoel. It ultimately leads to gastrula stage. It is a multilayered structure which is followed by organogenesis.