You throw a rock horizontally off a cliff with a speed of $20\frac{m}{s}$ and no significant air resistance. After $2\mathrm{.}0$ s $,$ the magnitude of the velocity of the rock is closest to

$28\frac{m}{s}$

$20\frac{m}{s}$

$40\frac{m}{s}$

$37\frac{m}{s}$