The correct option is B Population explosion
A population is a number of all the organisms of the same group or species who live in a particular geographical area.
Population explosion refers to the sudden and rapid rise in the size of the population, especially the human population.
Population growth is the increase in the number of individuals in a population.
Census is the procedure of calculating, acquiring and recording information about the members of a given population in a systematic way. Many countries take not only the census of humans but census of housing, manufacturing units, and agriculture.
Population genetics is branch of genetics deals with the genetic differences within and between populations. It is the study of the genetic composition of a population and the various factors affecting it.