Which definition most accurately describe what is an inductive proximity sensor?

Select one alternative:

inductive proximity sensor is a sensor that can measure the distance between objects

inductive proximity sensor is a sensor that can detect the presence of both metallic and

none metallic materials/objects

inductive proximity sensor is a sensor that can detect presence of objects made of

plastic, textile and liquids

Linductive proximity sensor is a sensor that can detect the presence of ferrous or

nonferrous metallic materials