An Alpha Particle with a Charge 2e and Mass 4m

Multiple Choice

An alpha particle with a charge 2e and mass 4m is moving with velocity v when it enters a magnetic field B at right angles to its direction of motion.A deuteron of charge e and mass 2m also enters the field in the same direction and the same speed.Calculate the difference in radius of motion between the alpha particle and the deuteron in the magnetic field region.

A) mv/eB
B) 0
C) 2mv/eB
D) mv/2eB
E) mv/4eB