In the southern subregion of sub-saharan africa, which country is mainly covered by the kalahari desert?
a. namibia
b. mozambique
c. zambia
d. botswana

Both Namibia and Botswana are mostly covered by the Kalahari Desert, along with few regions of Namibia. According to the geographical statistics, Botswana's seventy percent territory is covered by the Kalahari desert. That makes the option d. Botswana, the country mainly covered by the Kalahari Desert.