When the net force acting on an object is zero, the object is either at rest or moving at a constant velocity (which means it is not speeding up, slowing down, or changing direction). Therefore, the best answer among the options given would be:
The object is at rest.
However, note that it could also be moving at a constant speed. If your context allows for that interpretation, you might consider that as well. But strictly based on the provided options, "The object is at rest" is the most accurate response.