The first one, valleys. Rivers had to be built over, no one wanted their farms to be turned into a railroad (or at least those with common sense), and deserts had no water and was really hot during the day and cold at night.
The correct answer is - kilometers.
Very often, the map scale is showing distances in both miles and kilometers. The reason for this that the majority of the countries in the world use the metric system, thus the kilometers are a must, but also there countries that do not use this system, thus they include the miles. In this way, the map scale can be used by people that both use and not use the metric system in their daily lives.
The map scale is a very important element on the maps. Its purpose is to enable the reader of the map to be able to measure the distance from one place to another, thus to be aware of the real distance in the real space.
<span>An estuary is found at one end of a river delta wherein the freshwater from the river meets the saltwater from the ocean. It forms a transition zone between river environments to maritime environments. </span>I hope my answer has come to your help. God bless and have a nice day ahead!