Final answer:
The population of Africa South of the Sahara is approximately 900 million.
Step-by-step explanation:
The population of Africa South of the Sahara is approximately 900 million (option a). Africa is the second-largest continent in terms of population, with over 1.341 billion people in 2020. However, when considering only the area of Africa South of the Sahara, the population is estimated to be around 900 million.
It's important to note that population estimates can vary and change over time due to factors such as birth rates, migration, and data collection methods.