fertilization comes first
it is followed by cleavage which is the rapid cellular division which forms the blastula
then comes gastrulation where the 3 germ layers are formed.
followed by organogenesis which consists first forms the organs and then comes the specialization
Therefore your answer would be B
That they are <span>caused by microorganisms.</span>
Answer: Four conditions are needed for natural selection to occur: reproduction, heredity, variation in fitness or organisms, variation in individual characters among members of the population. If they are met, natural selection automatically results.
Explanation:
