What is the nature of the displacement-time graph of a body moving with constant velocity?

Identify what the graphs shown below indicate.

Using the following data,draw a time-displacement graph for a moving object:

Time $(s)$	$0, 2, 4, 6, 8, 10, 12, 14, 16$
Displacement $(m)$	$0, 2, 4, 4, 4, 6, 4, 2, 0$

Use this graph to find the average velocity for the first $4 \, s$,for the next $4 \, s$,and for the last $6 \, s$.

Draw velocity-time graphs for the following situations:
$(i)$ When a body is moving with uniform velocity.
$(ii)$ When a body is moving with variable velocity,but uniform acceleration.
$(iii)$ When a body is moving with variable velocity,but uniform retardation.
$(iv)$ When a body is moving with variable velocity and variable acceleration.

Four cars $A$,$B$,$C$ and $D$ are moving on a levelled road. Their distance versus time graphs are shown in the figure. Choose the correct statement.

What is a velocity-time graph? State how it can be used to find:
$(i)$ The acceleration of a body.
$(ii)$ The displacement of the body.
$(iii)$ The distance travelled in a given time.