The graph is missing, so I am using a graph for a similar question.
It migh even be the same question, but the important thing is that I am going to explain you the situation in several sections of this diagram and so you will be able to work this kind of problems by your selfl.
The graph is attached (see the figure).
The graph shows the evolution of the speed (vertical-axis) over time (horizontal-axis).
In the section A, the speed increases linearly: so the car is speeding up uniformly (constant acceleration).
In the section B, the line is horizontal which shows that the speed is constant. That is a uniform motion.
In the section C, the speed is decreasing uniformly, so the car is slowing down with uniform negative acceleration.
So, for this graph, the answer is: in the setion C. the car is slowing down (uniformly).