Which of the following map scales is the smallest?

The smallest map scale among the provided options is the one that represents the greatest area on the ground compared to the area on the map itself. When we examine the scales, a scale of 1:1,000,000 indicates that one unit of measurement on the map (e.g., an inch or centimeter) equals one million of the same units on the ground. This means that the area represented on the map is much larger compared to a scale of 1:25,000 or even 1:100,000.

In this context, smaller scale numbers like 1:25,000 represent a more detailed view of a smaller area, whereas higher scale numbers like 1:1,000,000 present a broader view, covering a larger geographical expanse. Therefore, 1:1,000,000 is the smallest scale, as it covers more area on the ground with less detail per unit of area shown on the map.