Final answer:
When a constant net external force acts on an object, the velocity may not change.
Correct option is; (a) position;
Step-by-step explanation:
When a constant net external force acts on an object, the velocity may not change. While the position, speed, and acceleration of the object may all change, the velocity remains constant if the net external force is constant.
When a constant net external force acts on an object, the position of the object may not change immediately. The change in position (displacement) depends on the initial conditions, the mass of the object, and the time the force is applied. If the force is applied for a very short time or if the object is initially at rest, the change in position may not be significant. The other options—speed, velocity, and acceleration—may change depending on the characteristics of the force and the object's mass.