Explanation: The ILS (Instrument Landing System) Localizer provides precise *lateral* guidance to the runway centerline. It transmits two VHF radio signals, typically amplitude-modulated at 90 Hz and 150 Hz, from antennas located at the far end of the runway. The 90 Hz signal's strength predominates to the left of the runway centerline, while the 150 Hz signal's strength is stronger to the right. An aircraft's receiver measures the difference in strength between these two signals. When the aircraft is exactly on the centerline, the signal strengths are equal. If there's an imbalance, the cockpit instrument displays a deviation indicating whether the aircraft is to the left or right of the desired course, allowing the pilot to correct. Therefore, the Localizer specifically indicates deviation left or right of the runway center line. Options B and C are incorrect as the Localizer does not provide information about ground speed. Option D is incorrect as wind speed is meteorological data, not part of the ILS navigation system. Vertical guidance for an ILS approach is provided by the separate Glideslope component.