Which of the following displacement $(X)$ time graphs is not possible?

What is common in the two graphs given below?

$Assertion$ : Velocity-time graph for an object in uniform motion along a straight path is a straight line parallel to the time axis.
$Reason$ : In uniform motion of an object velocity increases as the square of time elapsed.

The instantaneous velocity of a body can be measured by:

$A$ scooter accelerates from rest for time $t_{1}$ at a constant rate $a_{1}$ and then retards at a constant rate $a_{2}$ for time $t_{2}$ and comes to rest. The correct value of $\frac{t_{1}}{t_{2}}$ will be ..... .

The velocity-displacement $(v-s)$ graph shows the motion of a particle moving in a straight line. The velocity-displacement graph is a circle of radius $2 \ m$ and the center is at $(2, 0) \ m$. The value of acceleration for this particle at a point $(2-\sqrt{2}, \sqrt{2}) \ m$ will be $ms^{-2}$.