A ball of mass 3 kg moving with a velocity of `3 m//s` collides with another ball of mass 1 kg moving with velocity u in the opposite direction. If the first ball comes to rest after the impact and e=2/7, then u is in `m//s`, is

Options

A. `13/3`
B. `17/3`
C. `19/3`
D. `23/3`

Answer

C