Answer : option C
We analyze the attached graph
First, Ricky walked away from mall at the constant speed for 30 seconds
Second, he stopped walking for 40 seconds
Third, he walked towards mall at a constant speed for 10 seconds
Fourth , both walked away for next 20 seconds
So total walk time = 30 + 40 + 10 + 20= 100 seconds
Total time is 100 seconds. so we cannot choose option B and d because the graph ends before 100 seconds.
In option A, Ricky walked away from the mall after 70 seconds. so we cannot choose option A.
Option C is the graph best represents Ricky's motion.
