The following position vs time graph shows the motion of an object along its path from -10 to +15 seconds. From 10 seconds to 13 seconds, the velocity is negative due to the object moving from 10 m to m. That said, the velocity is a constant decrease a diagonal line). This means the velocity graph for this time should be what? A: flat ( horizontal ) line
B: diagonal line
C: parabola
D: cubic