Rain drops with $0\mathrm{.}5$ mm diameter can fall at $2\frac{m}{s}$ but $5$ mm diameter raindrops may fall as fast as $q,$

$0\mathrm{.}9\frac{m}{s}$

None of these

$900$ m$/$s

$90\frac{m}{s}$

$9\frac{m}{s}$