In common magnetic switch configurations, which form corresponds with a closed loop?

In the context of magnetic switch configurations, Form A is recognized as a normally open configuration. When no magnetic field is present, the circuit remains open. However, when a magnet approaches or is placed near the sensor, the circuit closes, allowing current to flow. This closure of the loop indicates a transition from an open state to a closed state, which is essential for triggering alarms or alerts in intrusion detection systems. Therefore, Form A corresponds to a closed loop when activated by the presence of a magnet, making it the appropriate choice for this question.