We know that radius of the path of a charged particle moving in a magnetic field can be give by the equation R = √(2mk)/qB , (m=mass,k= kinetic energy , q= charge ,B = Magnetic field)

As kinetic energy is same and they are moving in the same magnetic field

R(proton):R(alpha particle):R(deuteron) = √2mk/qb : √2.4mk/2qb : √2.2mk/qb = 1:1:√2