There are three mountains: the Sierra Madre Occidental, the Sierra Madre Oriental, and Sierra Madre del Sur.
Answer: El Salvador
Explanation: El Salvador has a population density of 303 people per square kilometer (785 per square mile).
Data visualization is the graphical representation of information and data. By using visual elements like charts, graphs, and maps, data visualization tools provide an accessible way to see and understand trends, outliers, and patterns in data.