To answer how the total momentum of the system has changed when the mass of the pink ball is altered to match the mass of the turquoise ball, we need to consider the principle of conservation of momentum.
If no external forces are acting on the system and you are only considering the change in mass of one of the balls (assuming their velocities remain constant), the total momentum of the system would generally stay the same.
Therefore, the correct response is:
the total momentum of the system stayed the same.