A solid sphere having mass m and radius r rolls down an inclined plane. Then fraction of its kinetic energy is :

$\frac{2}{5}$ rotational and $\frac{3}{5}$ translational energy

$\frac{1}{2}$ rotational and $\frac{1}{2}$ translational energy

$\frac{2}{7}$ rotational and $\frac{5}{6}$ translational energy

$\frac{5}{7}$ rotational and $\frac{2}{7}$ translational energy