ANSWER
D) all of the preceding
Step-by-step explanation
If the sum of the forces acting on an object is not zero, we call the resultant force a net force. Therefore, a net force is also called an unbalanced force.
By Newton's second law of motion, the net force acting on an object is,
In other words, a net force can produce the acceleration of the object.
Also, if the object is accelerating, it means that its velocity is not constant. Thus, a net force also produces a change in the velocity of the object.
Hence, the answer is all of the preceding.