What is the average drift speed of conduction electrons in a copper wire of cross-sectional area $1.0\times {10}^{-7}<mspace\; width="1em"></mspace>{\mathrm{m}}^2$ carrying a current of 1.5 A? Assume that each copper atom contributes roughly one conduction electron. The density of copper is $9.0\times {10}^3<mspace\; width="1em"></mspace>\mathrm{kg}/{\mathrm{m}}^3,$ and its atomic mass is 63.5 u. 

$1.<mspace\; width="1em"></mspace>1.1<mspace\; width="1em"></mspace>\mathrm{mm}<mspace\; width="1em"></mspace>{\mathrm{s}}^{-1}$
$2.<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>2.1<mspace\; width="1em"></mspace>\mathrm{mm}<mspace\; width="1em"></mspace>{\mathrm{s}}^{-1}$
$3.<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>3.1<mspace\; width="1em"></mspace>\mathrm{mm}<mspace\; width="1em"></mspace>{\mathrm{s}}^{-1}$
$4.<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>4.1<mspace\; width="1em"></mspace>\mathrm{mm}<mspace\; width="1em"></mspace>{\mathrm{s}}^{-1}$

Which one of the following is correct?