C. protein synthesis (they make proteins)
The food sources available for a particular species in an ecosystem. Also space where they can live and reproduce, but food is the main factor.
The answer is a trowel.
-Evidence—
•-A trowel is a small hand tool used for digging, applying, smoothing, or moving small amounts of viscous or particulate material. Common varieties include the masonry trowel, garden trowel, and float trowel.
First of all the reason the graph would be a curve is because, as the time increases the position changes, at first the ball is at a certain point then it starts rolling off a cliff so its moving foward and then the ball starts falling, (If too confusing here is a image http://www.mazzworld.net/U11Image1.gif)