The answer is: In the graph of displacement versus time, for something moving at a constant positive velocity, the line is straight and is going up. You can see it in the graph attached.
The explanation is shown below:
In a graph of displacement versus time, the displacement is on the y-axis and the time is on the x-axis. This type of graph that represents an object moving at a constant positive velocity, shows a linear function where the lines is straight and goes up (As you can see in the graph attached).
Then, the slope of the line is the velocity of the object and the y-intercept is the initial position.
