A body whose speed is constant

Four cars $\mathrm{A}$, $\mathrm{B}$, $C$ and $\mathrm{D}$ are moving on a levelled straight road, their distance-time graphs are shown in the given figure. Which of the following is correct statement regarding the motion of these cars?

In the speed-time graph for a moving object shown here, the part which indicates uniform deceleration of object is

The velocity-time graph given below, shows that the body has

A cyclist move from a certain point $\mathrm{X}$ and goes round a circle of radius $\mathrm{r}$ and reaches $\mathrm{Y}$, exactly on the other side of point $\mathrm{X}$. The displacement of the cyclist would be 

A body is moving as shown in the graph given below, representing the motion as