The larval forms of certain taenia species, which typically infest muscles of mammalian intermediate hosts is also called a

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.

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