Two ball `A` and `B` having masses 1kg and 2kg, moving with speeds `21m//s` amd `4m//s` receptively in opposite direction, collide head on. After collision `A` moves with a speed of `1m//s` in the same direction, then correct statements is:
A. `0.1`
B. `0.2`
C. `0.4`
D. none
