The sensor would just the distance then set off an alarm, the installation expert explained it was called a what kind of sensor?\nOptions:\n- near\n- closeness\n- here\n- proximity\n- this
Let's be accurate as possible and think first.
proximity
Proximity means nearness in space, time or relationship.

The sensor would just the distance then set off an alarm, the installation expert explained it was called a proximity sensor.

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Final answer: proximity