When two charged particles move toward each other, they experience an attractive force due to their charges. As they approach, their velocities decrease due to this force, and they eventually come to a stop at a certain point. After this point, the forces acting on them will cause them to accelerate.
Since they are charged particles (assuming they have opposite charges), after stopping, they will accelerate toward each other again due to the electrostatic attraction between them. Therefore, the correct response is:
They accelerate toward each other.