Final answer:
Zero acceleration means the object is moving at a constant velocity, which includes the possibility that the object is stationary or moving at a constant speed along a straight line.
Step-by-step explanation:
When the acceleration of an object is zero, it means that the object is not speeding up or slowing down, but it could be either at rest or moving at a constant speed in a straight line. This is known as motion at a constant velocity or uniform motion. The situation where the object's speed becomes zero is not applicable here, because zero acceleration only tells us that the speed is not changing, not that it is zero. If an object moves with constant velocity, it either maintains its speed and direction, or it is not moving at all (which can also be viewed as a constant velocity of zero).