A constant slope on a distance-time graph indicates what about the object's motion?

A constant slope on a distance-time graph signifies that the distance covered by the object increases uniformly over time. This uniformity means that for each unit of time, the object travels the same distance, which indicates a constant speed.

In terms of acceleration, since the speed does not change, the acceleration is zero. Therefore, the graph illustrates a situation where the object's motion is steady and consistent, with no increase or decrease in speed—this is why the option indicating that the speed is constant, resulting in zero acceleration, accurately describes the motion displayed in the graph.

The other descriptions do not apply in this case: an object that is accelerating would show a varying slope, an object at rest would be represented by a horizontal line (slope of zero), and deceleration would exhibit a negative slope, indicating a reduction in speed over time.