A bullet is shot vertically downwards with an initial velocity of...

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

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

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

$v = u + at$
$⇒ v = - 100 - 10 \times 10$
$⇒ v = - 200m{s}^{- 1}$

After $10s$ it hits the ground and remains at rest.

Therefore, option A is the correct representation.