The graph shows a bicycle rider's motion during the first portion of a race.
What conclusion can be drawn about the rider's motion?
A.
The rider maintained a constant speed during the time period between 0 and 10 seconds.
B.
The rider did not move during the time period between 10 and 15 seconds.
C.
The rider rode downhill during the time period between 15 and 20 seconds.
D.
The rider slowed down during the time period between 15 and 20 seconds.