Which one of the following represents the displacement-time graph of two objects $A$ and $B$ moving with zero relative velocity?

$A$ particle shows a distance-time curve as shown in the figure. The maximum instantaneous velocity of the particle is around the point:

The velocity $v$ of a particle is given by the equation $v = 6t^2 - 6t^3$,where $v$ is in $m/s$ and $t$ is time in $s$. Then:

Two cars $P$ and $Q$ start from a point at the same time in a straight line and their positions are represented by $x_P(t) = at + bt^2$ and $x_Q(t) = ft - t^2$. At what time do the cars have the same velocity?

$A$ particle is moving along the $Y$-axis. The position of the particle from the origin as a function of time $(t)$ is given as $y(t) = 10 t e^{-2 t}$. How far is the particle from the origin when it stops momentarily? ($y$ is given in units of metre and $t$ is in units of second)

For the velocity-time graph shown in the figure,what fraction of the total distance covered in all seven seconds is the distance covered by the body in the last two seconds of its motion?