The path followed by a projectile is called its a. projectile motion b. projectile path c. trajectory d. path of motion

The path followed by a projectile is called its trajectory. (C)

In the most common school situation ... with gravity but without air resistance, the trajectory of a projectile is the shape of an inverted parabola (nose  pointing up).  That's the result of constant horizontal velocity and accelerated vertical velocity.

3. dark matter

empty space could also be a simple vacuum