Final answer:
An inclined plane C) decreases the input forces needed by increasing the input distance, making it easier to move objects while keeping the work done the same.
Step-by-step explanation:
An inclined plane affects the work done on an object by decreasing the amount of input forces needed to move the object. This simple machine increases the input distance over which the force is applied, allowing a smaller force to move the object the same vertical distance as lifting it directly upwards would. The work done remains the same, as work is the product of force and distance. This principle is based on the conservation of energy within a closed system, where a machine cannot increase the total amount of energy. So, the inclined plane is useful because it changes the force and distance in such a way that the effort feels easier, although the total work done is unchanged.