What best describes a proximity sensor?

• A. A sensor able to detect the presence of nearby objects without any physical contact
• B. A device that requires physical contact to measure distance
• C. A sensor measuring temperature
• D. A sensor measuring pressure

Answer: (A)

A proximity sensor detects the presence of nearby objects without any physical contact. It works by sensing changes in a field or energy (such as magnetic, capacitive, optical, or infrared) caused by the nearby object, so it can indicate presence without touching the object. This non-contact nature distinguishes it from sensors that require touch to measure distance or to sense a physical quantity like temperature or pressure. The description that emphasizes detecting nearby objects without contact captures what a proximity sensor does, while the other options describe sensors that measure temperature or pressure or that need contact to determine distance.