A proton $($Mass $=1\mathrm{.}672{10}^{-27}kg$ and charge $=1\mathrm{.}6{10}^{-19}C)$ moving horizontally to the right at a speed of $2\mathrm{.}00{10}^6\frac{m}{s},$ enters a $1\mathrm{.}80$ mT downward magnetic field. The radius of rotation of the proton caught in this magnetic field is

$2\mathrm{.}85$m

$11\mathrm{.}6$ m

$4\mathrm{.}72m$