List 3 or more factors that have caused human population to increase in the modern era?

Three primary factors and explanations behind population growth, are the following: 
1. Decrease in death rate: With the progress of solution, individuals today have possessed the capacity to discover a cure for different maladies. These medicines have helped in drawing out their future. Consequently, the death rate today has tumbled down. 
2. Increase in birth rate: Better nutritional system today has empowered the fertility rate to increase. Medications and drugs, help ladies in pregnancy, consequently prompting an expansion in birth rate. 
3. Relocation: Individuals move from one place then onto the next for different reasons. This relocation has caused an expansion in population in different spots. 

A, c, and d are the answers

Ibelieve the answer to this question is a