I think carbon dioxide would be a correct answer, but you didn't post the possible answers
Cells are the basic building blocks of all living things. The human body is composed of trillions of cells. They provide structure for the body, take in nutrients from food, convert those nutrients into energy, and carry out specialized functions.
Hope this helps
-lvr
The answer would be A. Rock Formation because after the crust is cooling it starts to form a new rock formation, which would be the next step in the project. Hope this helped! :D
It was used till the 1960s. Hope i helped.