Of the following machines, which is not related to the others?

ramp

screw

lever

Answer;

Lever

Explanation;The two basic families of simple machines are the lever family and the inclined plane family. The lever family includes; the simple lever, the pulley and the wheel and axle while the inclined plane family includes; the simple inclined plane, the wedge and the screw.Ramps are among examples of inclined planes, together with others such as sloped roads and hills,  plows, wedges, hatchets, etc.Therefore, ramps and screw are related as they are examples of machines in inclined plane family.

The correct answer is: a