Increase in population is due to:

The correct answer is Option (2) → Natality and Immigration

Option (1) Emigration and Mortality — Incorrect. Both of these remove individuals from the population, so they decrease it.

Option (2) Natality and Immigration — Correct. Both of these add individuals to the population: new births and new arrivals of the same species.

Option (3) Immigration and Emigration — Incorrect. Immigration adds individuals, but emigration removes them. The pair works in opposite directions.

Option (4) Mortality and Natality — Incorrect. Natality adds, but mortality removes. The pair works in opposite directions.

NCERT Extract:
Population Growth – “The size of a population for any species is not a static parameter. It keeps changing with time, depending on various factors including food availability, predation pressure and adverse weather. In fact, it is these changes in population density that give us some idea of what is happening to the population – whether it is flourishing or declining. Whatever might be the ultimate reasons, the density of a population in a given habitat during a given period, fluctuates due to changes in four basic processes, two of which (natality and immigration) contribute to an increase in population density and two (mortality and emigration) to a decrease.”