$(5$ pts$)13.$ A uniform solid cylinder is rolling without slipping on a horizontal surface. The moment of inertia of the cylinder about its rotation axis is $I=\frac{1}{2}M{R}^2.$ What fraction of the total kinetic energy is rotational?

$($a$)\frac{1}{2}$

$($b$)1\mathrm{.}13$

$($c$)21\mathrm{.}5$

$($d$)\frac{2}{7}$

$($e$)\frac{2}{3}$

$($f$)$ none of the above

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