According to the principle of conservation of momentum, the total momentum of a closed system before and after a collision remains constant, provided no external forces are acting on it.
In this case, the total momentum before the collision is \(3 , \text{kg⋅m/s}\). After the collision, regardless of how the momentum is distributed among the balls, the total momentum of all the balls (including the original moving ball and the three struck balls) will still be \(3 , \text{kg⋅m/s}\).
So, the correct response is:
3 kg⋅m/s.