Which graph corresponds to an object moving with a constant negative acceleration and a positive velocity?

The displacement-time graphs of two moving particles make angles of $30^{\circ}$ and $45^{\circ}$ with the time-axis as shown in the figure. The ratio of their respective velocities is:

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 $ms^{-2}$.

The position of a particle moving along the $x$-axis is given by $x = 10t - 2t^2$. Then the time $(t)$ at which it will momentarily come to rest is .......... $s$.

The positions of two cars $A$ and $B$ are given by $X_A = at + bt^2$ and $X_B = ft - t^2$. At what time will both cars have the same velocity?

The following plots show the variation of velocity $(v)$ with time $(t)$ for a ball thrown vertically upward and falling back. Which of the following plots is correct?