Human development begins with a(n)

which is created when

join and thdas

first cell division takes place

Zygote, the nucleus of  male and female gametes join, mitosis

Explanation:

The human belongs to the animal kingdom which begins their life when the male and female gametes fuse through a process called Fertilization.

The process of fertilization involves the fusion of the nucleus or the genetic material of the male and female gametes. The process forms a diploid cellular structure called the zygote. After the formation of the zygote, the first cell division or mitosis produces the embryo which develops into an organism.

the earth is thought to have been formed about 4.6 billion years ago by collisions from a cloud of hydrogen, helium, rock, ice and other materials. these were pulled together by gravity to form objects in and around earth like- asteroids and small early planets called planetesimals.

so, the best possible answer to this question will be option d- to harden materials to form different parts of earth’s layers