$A$ proton (mass $m$ and charge $+e$) and an $\alpha$-particle (mass $4m$ and charge $+2e$) are projected with the same kinetic energy at right angles to a uniform magnetic field. Which one of the following statements will be true?

• A
  The $\alpha$-particle will be bent in a circular path with a smaller radius than that of the proton.
• B
  The radius of the path of the $\alpha$-particle will be greater than that of the proton.
• C
  The $\alpha$-particle and the proton will be bent in a circular path with the same radius.
• D
  The $\alpha$-particle and the proton will go through the field in a straight line.