The best answer is C. Botswana. 70 percent of the territory of Botswana is covered by the desert. Kalahari also covers, but less so, the areas of Namibia and South Africa.
Botswana is a topographically flat country wherein 70
percent of its territory is the Kalahari Desert. Because Botswana is bordered
by South Africa to the south and southeast area of its territory and by Namibia
to the west and north territory, minimal land areas of both countries are included
in the 900,000 square kilometer land area of Kalahari Desert.
Kalahari Desert also encroached on some parts of Zambia but
no part of Mozambique.