A $1$ kg ball initially moving at $2$ m$/$s perpendicular to a wall rebounds from the wall with a final speed of $1\mathrm{.}5$ m$/$s$.$ The magnitude of the initial momentum is:

$2$ kg$.$m$/$s

$1\mathrm{.}5$ kg$.$m$/$s

$3$ kg$.$m$/$s

$0\mathrm{.}5$ kg$.$m$/$s