Hi there!
<u>Curved graph. </u>
For an object undergoing projectile motion, the HORIZONTAL component of its remains constant (assuming no air resistance), while the VERTICAL component is changing due to a constant acceleration due to gravity.
We can relate vertical displacement vs. time to this acceleration using the kinematic equation:

dy = displacement (m)
vy₀ = initial vertical velocity (m/s)
t = time (s)
a = acceleration due to gravity (m/s²)
This is an example of a QUADRATIC equation, which means the trajectory of a projectile would form a parabolic shape.
<u>Thus, it would be a curved graph.</u>