Final answer:
The slope of a velocity-time graph represents the acceleration of the object. This is because acceleration is defined as the rate of change of velocity over time.
Step-by-step explanation:
The kinematic quantity equivalent to the slope of a velocity-time graph is acceleration. On a velocity versus time graph, if the velocity is increasing or decreasing at a constant rate, the slope of the line is straight, indicating constant acceleration. The steeper the slope, the greater the acceleration. Conversely, if the line is horizontal, the slope is zero, indicating no acceleration and constant velocity. Thus, the correct answer to the original question is b) Acceleration.
Furthermore, to clarify related concepts, the area under a velocity-time graph provides the displacement of the object. It's also worth noting that on a position versus time graph, the slope represents velocity, not acceleration or displacement.