A thematic map is designed to highlight a specific theme or variable across a geographic area. Among the options provided, the information that would be displayed in a thematic map is:
- Median income in different U.S. states.
This type of map would visually represent the varying median income levels across different states, differentiating the areas based on this specific data. The other options, such as the size of age and sex cohorts, the counties and cities within a state, and the major landforms, are not typically presented in thematic maps.