A heavy steel ball of mass greater than 1 kg moving with a speed of 2 m sec^-1 collides head on with a stationary ping-pong ball of mass less than 0.1 gm. The collision is elastic. After the collision the ping-pong ball moves approximately with speed

• A

  $2\mathrm{m}{\sec }^{-1}$

• B

  $4\mathrm{m}{\sec }^{-1}$

• C

  $2\times {10}^4\mathrm{m}{\sec }^{-1}$

• D

  $2\times {10}^3\mathrm{m}{\sec }^{-1}$