Please please please answer this question for me THANK YOU!!! 40 POINTS

Step-by-step explanation:

The vertical axis represents distance traveled, and the horizontal axis represents time.

At the beginning, time = t = 0 and distance = d = 0.

Between t = 0 and t = 20, the group moved in the positive direction by 40 units.  Then, between t = 20 and t = 60, they stayed where they were, at distance 40 units from the origin.  (Slope of graph is zero; this means the rate of travel is zero.)

Between t = 60 and t = 120, the group moves further away from the origin (actually, further away from Point C, reaching Point D, which is 150 units from the origin.  

Between t = 120 and t = 160, the group is at rest / does not move.

Between t = 160 and t = 200, the group moves back to the origin (distance = 0) at a steady rate.

a is the correct