Simple machines help in reducing the magnitude of effort required. Example, machine with force multiplier more than 1.
They also help to change the point of application of effort to a convenient point. Example, a bicycle.
They also help in increasing the distance travelled by the load, example, machine with speed multiplier more than 1.
Simple machines also changes the direction of effort to a convenient direction, example, a pulley, it is easier to apply force downward than upward.
Options A, B and C correspond to the cases listed above.
Option D is not a function of simple machine.