Two protons whose velocities are in the ratio $4 : 1$, move perpendicular to a uniform magnetic field, the ratio of the radii of their paths will be

Question

$\begin {array} {1 1} (a)\;1:1 & \quad (b)\;2:1 \\ (c)\;4:1 & \quad (d)\;1:4 \end {array}$