Explanation: The "dots" on a radar display at a specified range typically refer to the range rings, which are concentric circles indicating distance from the radar's own ship. The spacing of these range rings is a convention used to help operators quickly estimate the distance to targets. For many radar systems, especially those set to shorter ranges like 5 nautical miles (nm), a common practice is to have range rings spaced at intervals that are a convenient fraction of the maximum range. A widely used interval is 5/8 of a nautical mile. Calculating this for a 5 nm range setting: 5 nm / 8 = 0.625 nm. Therefore, the approximate distance between these range rings (dots) at a 5 nm display setting would be 0.625 nm. Option D, 0.64 nm, is the closest approximation to this standard radar display convention. Other options represent less common or non-standard range ring intervals for a 5 nm scale.