Alpha Particles, Each Having a Charge of +2e and a Mass

Multiple Choice

Alpha particles, each having a charge of +2e and a mass of 6.64 ×10^-27 kg, are accelerated in a uniform $0.50 \mathrm {~T}$ magnetic field to a final orbit radius of $0.50 \mathrm {~m}$ The field is perpendicular to the velocity of the particles. What is the kinetic energy of an alpha particle in the final orbit? (1 eV = 1.60 × 10^-19 J, e = 1.60 × 10^-19C)

A) 3.0 MeV
B) 2.6 MeV
C) 3.4 MeV
D) 3.9 MeV
E) 4.3MeV