Answer:
Option D
Explanation:
(D) The sentence refers to the relative impacts of cultural and biological influences on cross-cultural diversity (meaning diversity in culture within the same population). The second port says categorically that the fact is that, in countless aspects of human existence, it is the cultural programming that overwhelmingly accounts for cross-population variance. Since this is contrasted with the notion hinted in the first part of the sentence (by the use of the phrase 'discredited by the fact'), that notion must be either that it is the biological influences that have such an overwhelming impact, or that the biological influences have at least as strong an impact as cultural influences over cross-cultural diversity. Among the choices, the word equally lends the second of these meanings to the given sentence, and is the answer.