What does a 'D' following the identifier on a VOR page indicate?

The presence of a 'D' following the identifier on a VOR page indicates that the VOR has paired DME (Distance Measuring Equipment). This means that in addition to providing radial information for navigation, the VOR facility is equipped with DME, allowing pilots to receive distance information from the VOR. This is beneficial for situational awareness and navigation accuracy, as it allows a pilot not only to know their position relative to the VOR but also how far they are from it.

The other options do not accurately reflect what the 'D' signifies. For example, a high altitude VOR or a low frequency VOR would not be indicated by the presence of a 'D'. Similarly, the designation would not apply if the VOR were unused, as the 'D' specifically denotes functionality, particularly the pairing with DME technology. Thus, the identifier with a 'D' is a clear communication of enhanced navigational capabilities provided by the integration of DME with the VOR station.