The process of dna replication is called semi conservative because it results in

the process of DNA replication is called semi conservative because it results in two DNAs having a new strand and a old strand which is from the original DNA molecule

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