Proton, Deuteron and alpha particle of the same kinetic energy are moving in circular trajectories in a constant magnetic field. The radii of proton, deuteron and alpha particle are respecctively $r_p$, $r_d$ and $r_{\alpha}$. Which one of the following relations is correct ?

Question

( A ) $r_{\alpha} > r_d > r_p$
( B ) $r_{\alpha} = r_p < r_d$
( C ) $r_{\alpha} = r_p = r_d$
( D ) $r_{\alpha} = r_d > r_p$