What happens to the ADF bearing pointer upon detecting an NDB station?

When an Automatic Direction Finder (ADF) detects a Non-Directional Beacon (NDB) station, the bearing pointer provides critical information about the aircraft's heading relative to the NDB. The correct answer indicates that the ADF bearing pointer points towards the NDB station; this is essential for navigation.

The direction indicated by the ADF bearing pointer can help pilots determine the relative position of the station in relation to their current flight path, allowing them to make informed decisions regarding their course.

The other options do not accurately reflect the behavior of the ADF bearing pointer. If the pointer were to vanish, it would suggest a failure in the system, which is not the standard operating characteristic. A pointer moving to the east would imply a predetermined movement irrelevant to the actual position of the NDB; ADF readings are based on the aircraft's position and the station's location, not arbitrary directional movement. Rapid spinning of the pointer would indicate a malfunction or loss of signal, rather than a standard operational response to detecting an NDB. Thus, the pointer accurately indicating the direction of the station is the appropriate function being tested in this question.