The correct answer is D. The majority of the country's population is under 20 years old.
In July 2011 its population was estimated at 2,065,398 inhabitants. Botswana, like many nations in southern Africa, suffers from a high rate of AIDS infection, estimated in a 2002 UN report at 38.8% for adults.
32.4% of the population is aged between 0 and 14 years old, 63, 47% is aged between 15 and 64 and 4.13% is aged 65 or over. The country is growing at a rate of 1.19% per year in 2016, with a birth rate of 20.7%, a mortality rate of 13.3%, an infant mortality rate of 8.6%, a fertility rate of 2.3 children per woman and a migration rate of 4.5 %.
In the graphic we can watch the percent of population according to age in Botswana.