A bullet is shot vertically downwards with an initial velocity of 100   m   s - 1 from a certain…

As the upward direction is taken as positive, the velocity at $t=0$ is $u=-100 \mathrm{m} {\mathrm{s}}^{-1}$.

As it is falling under gravity, its acceleration is constant and $a=-10 \mathrm{m} {\mathrm{s}}^{-2}$.

Applying equation of motion for constant acceleration during the time of fall i.e., for $0$ to $10 \mathrm{s}$,

$$\begin{gathered} v=u+at \\ \Rightarrow v=-100-10\times 10 \\ \Rightarrow v=-200 \mathrm{m} {\mathrm{s}}^{-1} \end{gathered}$$

After $10 \mathrm{s}$ it hits the ground and remains at rest.

Therefore, option A is the correct representation.