Answer: The correct answer is -
The birth rate decreased, while the death rate increased.
Growth of population primarily depends on the factors-
birth rate, death rate, immigration rate, and emigration rate
Population change or population growth can be calculated by using the following equation-
r = (b-d) + (i-e)
Where, r= growth rate
b= birth rate (number of births per thousand of population in an year)
d= death rate (number of deaths per thousand of population in an year).
i= immigration rate (people coming in the area)
e= emigration rate (people exiting/leaving from the area).
Thus, if the birth rate decreased, while the death rate increased, it will lead to overall decrease in the population of a species.