Answer;
Decreased birthrate
If immigration and emigration numbers remain equal , decreased birthrate could cause a slowed growth rate.
Explanation;
All populations change in size with time . Change in population is dependent of various factors, namely; birthrates, death rates, immigration and emigration.
Therefore; change in population size would be given by the difference of the sum of birth rates and immigration and the sum of death rates and emigration. That is; Change in Population Size = (Births + Immigration) - (Deaths + Emigration). A decreased birth rate with emigration and immigration remaining constant would cause a slowed growth rate.
