If the current density in a wire is given by $Rk{R}^{2}2k\frac{R^3}{3}k\frac{R^3}{3}k\frac{R^2}{2}3k\frac{R^3}{2}j=kr,0,$ where $Ris$ the radius $of$ the wire, the current $in$ the wire $is$

$k{R}^2.$

$2k\frac{R^3}{3.}$

$k\frac{R^3}{3.}$

$k\frac{R^2}{2.}$

$3k\frac{R^3}{2.}$