Answer:
because people where not alive yet oontill cenoznic era
Explanation:
Lithosphere-rock
Hydrosphere-water
Atmosphere of earth - air
They help us and earth survive everyday
B because it sets the scene and describes what it is like!
The blank should be digestion (process).
The action of cutting food into smaller pieces with teeth is a physical change/digestion, because this action does not involve enzymes, which are necessary for chemical digestion, examples are such as turning starch to Maltose.
The action of cutting and crushing food can increase the surface area, so that it can speed up the chemical digestion later on and provide the most nutrients for the body.
