A $2\mathrm{.}0-kg$ stone is tied to a $0\mathrm{.}50$ m long string and swung around a circle at a constant angular velocity of $12ra\frac{d}{s}.$ The circle is parallel to the $xy$ plane and is centered on the $z$ axis, $0\mathrm{.}75$ m from the origin. The magnitude of the torque about the origin is:

$0N*m$

$6\mathrm{.}0N*m$

$14N*m$

$72N*m$

$108N*m$