A ball of mass m moving with velocity V, makes a head on elastic collision with a ball of the same mass moving with velocity 2V towards it. Taking direction of V as positive velocities of the two balls after collision are

• A

  $-\mathrm{V} \mathrm{and} 2\mathrm{V}$

• B

  $2\mathrm{V} \mathrm{and} -\mathrm{V}$

• C

  $\mathrm{V} \mathrm{and} -2\mathrm{V}$

• D

  $-2\mathrm{V} \mathrm{and} \mathrm{V}$