The scenario that accurately describes magnitude and direction is:
A car traveling northward with 5 kN of force could be brought to a stop by a southward force of 5 kN.
This is because the southward force of 5 kN would exactly counteract the northward force of 5 kN, resulting in a net force of zero, which would bring the car to a stop.
The other options either suggest incorrect forces (e.g., 5 kg is a mass, not a force) or do not represent a situation where the forces balance out correctly to stop the car.