Correct sequence in development is
a)	Fertilization  zygote  cleavage  morula  blastula  gastrula
b)	Fertilization  zygotes  blastula  cleavage  gastrula
c)	Fertilization  cleavage  morula  zygote  blastula
d)	cleavage  zygote  morula  zygote  blastula

(a)

Correct sequence in development is fertilisation (union of male

of male and female gamete)

Zygote (syngany or amphioxis) leads to the zygote)

Cleavage (series of rapid mitotic division of the zygote)

Morula (8-16 blastomere structure called morula having similar types of cells)

Blastula (more than 16 blastomere (approx.-64) it is hollow structure

With blastocoel cavity in center)

Gastrula (Transformation of the blastocyst in the gastrula with primary germ layer by rearrangement a cell called gastrulation and structure is called gastrula)