Answer:
The absolute value of the slope of a position-time graph.
Step-by-step explanation:
The slope in a time position graph is the derivative of the position with respect to time.
This derivative of the position with respect to time is what is known as velocity, which is a vector quantity.
Speed is the absolute value of velocity, since it is a scalar quantity, it has no sign and no direction.
So the correct answer is that speed is the absolute value of the slope in a graph of position and time.