Concept:Population growth rate depends on the difference between birth rate and death rate.
Explanation:In West Africa, the birth rate remains very high.
At the same time, better healthcare and improved sanitation have lowered the death rate.
When births far exceed deaths, the population grows rapidly.
Birth control policies would reduce growth, not increase it.
A low birth rate with a high death rate would cause population decline.
Immigration is not the main cause of West Africa's natural population increase.
Answer:High birth rate and low death rate.