Answer:
In the course of evolution mammals are the animals which are evolved recently as compared to other groups such as fish, amphibians, or reptiles.
In addition, fur or hairs on body, mammary glands, middle ear bone, warm-blood, et cetera are the characteristics of mammals.
These characteristics were evolved during the course of evolution; they were not present in ancestral organisms.
However, tail, gill pouches, et cetera are characteristics of our ancestral groups. Thus, characters can be sometimes observed in mammals.
But mammals characteristics can not be observed in organisms which were evolved before mammals such as fishes, amphibians, reptiles, et cetera.
<span> After fertilization, the </span>zygote<span> undergoes cleavage to form the blastula. The blastula, which in some species is a hollow ball of cells, undergoes a process called gastrulation, in which the three germ layers form.</span>
A. Nutrients, vitamins would also be a correct answer
C.it changes DNA,but it is random
