Population density is a key geographic term that is used to measure the population per unit area. Generally, it is used in terms of human populations. In reference to living organisms, the population density is the population divided by total land area.
The density of population or population density is simply a quantity of type number density which measures the number of people living in an area. The unit of measurement is population per square kilometer. It is a key geographical term that depicts the favorable conditions preferred by communities and fertility of the land. The regions which are densely populated show that they have fertile plains with favorable climate. Highly industrialized and urban lands are also lands of a high density of population.
Various places with a high density of population are East Asia, South, and South-east Asia, North-West Europe, and The Northeastern Coast of North America. These regions have a population density of more than 200 persons per square kilometer. Countries like Norway and Sweden have moderate population densities.
The population density not only tells about the number of people living in an area but it also relates to the population change. Population change further determines the rate of the beneficence of the growing economy.
There are various factors that affect the density of the population. These factors are the availability of water, climate, soils, industrialization, social and cultural factors, etc.
Therefore, from the above discussion, we can conclude that the density of population indicates the ratio between the Man that is population and land.
Hence, option D is correct.
It is known that a small increase in the population density is beneficial for a growing economy. But every land has its specified carrying capacity to hold a particular number of populations. Growth beyond the carrying capacity of a region leads to resource depletion. This leads to population decline.