The correct answer is because they have been childless for years.
Explanation:
The story of "No witchcraft for sale" by Doris Lessing talks about the Farquars' family. They lived in the south of Rhodesia and had a child named Teddy. At the beginning of the story says that "The Farquars had been childless for years when little Teddy was born"
The Sahara is a desert located in northern Africa (as you can see in the map). And one of the only answer countries in proximity to that desert is Mali, so the answer would be C.