Which of the following describes population density?

Population density is defined as the number of people living per unit area, often expressed as individuals per square kilometer or square mile. This measure helps to understand how crowded or spaced out a population is within a specific geographic area, particularly in urban settings where land is often limited and demand for space is high.

In urban environments, population density can significantly impact various aspects of city life, such as housing, transportation, and infrastructure. Higher population density typically leads to increased demands on services and resources, while lower density might suggest more available space and potentially less strain on these services. The focus on urban settings is crucial, as cities tend to have higher population densities compared to rural areas, where the population is more dispersed.

The other options do not capture the essence of population density. For example, discussing the total number of people in a rural area focuses simply on population size without considering area, while variations in demographics over time and employment rates in urban centers pertain to different aspects of population studies rather than density itself.