Which of the following statements best describes fertility rates in sub-Saharan Africa? A. Fertility rates are among the lowest in the world, so populations are shrinking. B. Fertility rates are among the highest in the world, so populations are growing quickly. C. Fertility rates are at the world average, so populations are growing at an average rate. D. Fertility rates are at the replacement rate, so populations are staying about the same. Please select the best answer from the choices provided