On Earth, when a box slides across a horizontal board, the board exerts a frictional force of magnitude $\backslash ($ F$\_\{0\}\backslash )$ on the box. The board and the box are moved to a planet with twice the radius but one$-$third the mass of Earth. When the box slides across the board, the frictional force exerted by the board on the box is now

$\backslash [$

$($

$\backslash ]$

$($B$)\backslash (\backslash$frac$\{1\}\{6\}$ F$\_\{0\}\backslash )$