$18)$ If a flea can jump up to $45$ cm above its initial starting point, with what speed is it able to leave the ground when jumping?

A$)3\mathrm{.}0$ m$/$s

B$)$

$8\mathrm{.}8$ m$/$s

v$=1200$

$2\mathrm{.}1$ m$/$s

$4\mathrm{.}2$ m$/$s