The $x – t$ graph shown in figure represents

Which of the following curves does not represent motion in one dimensions?

The displacement-time graph for two particles $A$ and $B$ are straight lines inclined at angles of ${30^o}$ and ${60^o}$ with the time axis. The ratio of velocities of ${V_A}:{V_B}$ is

For the displacement-time graph shown in figure, the ratio of the magnitudes of the (constant) speeds during the first two seconds and the next four seconds is

The displacement of the particle varies with time according to the relation $x = \frac{k}{b}\,[1 – {e^{ – bt}}]$. Then the velocity of the particle is