The correct answer is - B. low birth rates.
The less-developed countries do not have a low birth rate, but instead they are the countries that in general have the highest birth rates in the world. Because of the very high birth rate, these countries face even bigger problem, because the political, economic, social situation is not improving or is improving but very slowly, but the population is rapidly growing, which leads to bigger unemployment, lack of food and resources, and conflict.
