Two bullets are fired horizontally with different velocities from the same height. Which one will reach the ground first?

The correct option is C Both will reach simultaneously
Since both the bullets are fired horizontally, vertical component of velocity for both the bullets will be zero. Also both are fired from the same height.
From $2^{nd}$ equation of motion for vertical displacement$(-h)$,
$S=V_{y}t+\frac{1}{2}g{t}^2$
$-h=0-\frac{1}{2}g{t}^2$
$t=\sqrt{2gh}$
Also both bullets experience gravitational acceleration $(-g)$ in downward direction.
Hence both will take equal time to reach the ground