Two cars of masses $m_{1}$ and $m_{2}$ are moving in circles of radii $r_{1}$ and $r_{2}$ respectively. Their speeds are such that they make complete circles in the same time $t$. The ratio of their centripetal force is

• A
  $m_{1}: m_{2}$
• B
  $r_{1}: r_{2}$
• C
  $1: 1$
• D
  $m_{1} r_{1}: m_{2} r_{2}$