Which description of black Africans is most accurate?

Which description of black Africans is most accurate?
 
  a. They comprise 60 of the population, are a culturally unified group, have lost fluency in their native tongue, and practice nativist religion customs.
  b. They comprise 60 of the population, are derived from several Bantu tribes, speak their native tongue, and are at least nominally Christian.
  c. They comprise 80 of the population, are a culturally unified group, have lost fluency in their native tongue, and practice nativist religion customs.
  d. They comprise 80 of the population, are derived from several Bantu tribes, speak their native tongue, and are at least nominally Christian.

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What is the single overriding criterion of societal power in South Africa?
 
  a. Religious affiliation
  b. Tribal classification
  c. Skin color
  d. Monopolization of gems