Magnetic Effects of Current and Magnetism: JEE Main 2021 Physics question

A proton and an $\alpha$-particle, having kinetic energies K_p and K_$\alpha$ respectively, enter into a magnetic field at right angles. The ratio of the radii of trajectory of proton to that of $\alpha$-particle is 2 : 1. The ratio of K_p : K_$\alpha$ is :