Alright, from the graph, we know that Hannah's distance between hour 2 and hour 4 isn't uniform, so what we need to do is break the graph down a little.
When we break it down, we learn that Hannah's distance between hour 2 and hour 3 is decreasing because the y value decreases, and that Hannah's distance between hour 3 and hour 4 is increasing, because the y value starts increasing again.
Once we know that, all that's left is to match it up with the choices given. We can eliminate choices A and D because Hannah's distance between hour 2 and hour 4 isn't uniform, leaving us with B and C.
Between hours 2 and 3, we know that Hannah's distance is decreasing because the y value decreases, giving you your answer, which is C!