Ball $P$ of mass $m$ moving with velocity $v$ collides with another ball $Q$ of mass $2m$, which is at rest. If $v_P$ and $v_Q$ are the final velocities of $P$ and $Q$ respectively after the collision, then (Assume the coefficient of restitution is $e = 1/3$):

• A
  $\frac{v_Q}{v_P} = 4$
• B
  $\frac{v_P}{v_Q} = 4$
• C
  $\frac{v_Q}{v_P} = 2$
• D
  $\frac{v_P}{v_Q} = 2$