Demography is a branch of science that deals with the study of human population. The populations are dynamic and change based on the factors like birth, migration, aging and death, etc. Therefore, option (a) is incorrect.
The highest number of individuals of a particular population that an ecosystem can support is called as the carrying capacity. The population depends on the environment for the basic necessities like the food, water, habitat, etc. the maximum population that can be sufficiently supported by all these factors by the ecosystem is called the carrying capacity. Therefore, option (b) is incorrect.
Immigration refers to the number of individuals that enter into a geographical at a given time. It is the movement of people into a country or region which they are not native. Immigration can occur due to many reasons. They include in search of livelihood, breeding, natural disaster, poverty, political causes, etc. Therefore, option (c) is correct.
Emigration refers to the number of individuals that move out of a geographical area at a given pint of time. This can be of different reasons that include extreme climatic conditions, natural disaster, poverty, political causes, deficiency of basic resources, etc. Therefore, option (d) is incorrect.
Hence, the movement of the individuals in to an area is called as (c) immigration.