Magnetic Effects of Current and Magnetism: JEE Main 2019 Physics question

A proton and an $\alpha$-particle (with their masses in the ratio of 1 : 4 and charges in the ratio of 1 : 2) are accelerated from rest through a potential difference V. If a uniform magnetic field (B) is set up perpendicular to their velocities, the ratio of the radii r_p : r_$\alpha$ of the circular paths described by them will be ;