Final answer:
A special purpose map would be used to show population density in the countries of the world.
Step-by-step explanation:
The type of map that would be used to show population density in the countries of the world is a special purpose map. Special purpose maps are designed to focus on a specific theme or topic, such as population density. They use different symbols and colors to represent the concentration of population in different areas. For example, darker colors might be used to show higher population density while lighter colors might be used to indicate lower population density. These maps provide visual representations of population patterns and can help us understand how population is distributed across different countries.