Final answer:
The distance between two cities is best measured in kilometers, as this is the standard unit for long distances in the metric system.
Step-by-step explanation:
To accurately measure the distance between two cities, we would use kilometers (km). Kilometers are the longest unit of metric measurement commonly used for measuring long distances such as the one from one town to another. Since there are 1,000 meters in a kilometer, kilometers are much better suited for larger distances than meters, which are typically used for shorter lengths such as the size of a house or pool. Therefore, when considering the appropriate unit of measurement for the distance between two cities, kilometers are the best choice. Not only are they more practical, but they also align with the standard metric units of measurement used in the majority of the world for scientific and navigational purposes.