The answer is
D. another natural disturbance
Answer: In Stage 4 of the Demographic Transition Model birth rates and death rates are both low, stabilizing total population growth. The decline in both birth and death rates of most Stage 4 countries have been attributed to strong economies, highly educated citizens, ample healthcare systems, the migration of people from rural communities to cities (Bulgaria)
Explanation: i dont know if it's correct to them
The answer is B) Genetic variation
