Answer:
Option C is the correct answer.
Explanation:
We have velocity of a body = Change in position/ Time.
Considering first portion of graph,
Change in position = 30 - 0 = 30 m
Time = 0.75 hours = 45 minutes = 2700 seconds
Velocity = 30/2700 = 0.011 m/s
Considering second portion of graph,
Change in position = 30 - 30 = 0 m
Time = 0.5 hours = 30 minutes = 1800 seconds
Velocity = 0/1800 = 0 m/s
Considering third portion of graph,
Change in position = 0 - 30 = -30 m
Time = 0.75 hours = 45 minutes = 2700 seconds
Velocity = -30/2700 = -0.011 m/s
So firstly they walked in one direction(positive direction), then they were still(velocity is zero), then they walked in the opposite direction( velocity is negative).
Option C is the correct answer.