The slope of a(n) graph represents speed

The answer is Distance-Time graph.

Explanation:

Firstly, we have to know a distance-time graph. I have attached two images that show a distance-time graph and different type of slopes.

In a distance-time graph, the gradient of the line is equal to the speed of the object. The greater the gradient, the faster the object is moving.

In order to determine the slope, we have to do:

As we see in the first image, the diagram shows, after drawing the tangent, work out the change in distance (A) and the change in time (B).

Velocity, a vector quantity, changes if either the magnitude or the direction changes. This is important when dealing with circular motion.

whichever one it is, it's definitely not one that you included on the list you provided.

the answer would be a