各位大大好，小弟在做陳聖元的時候遇到一題想不通的題目，敢請大家解惑。
The notion that cultural and biological influences ____ determine cross-cultural diversity is discredited by the fact that , in countless aspects of human existence , it is cultural programming that overwhelmingly accounts for cross-population variance.
(A) jointly
(B) completely
(C) directly
(D) equally
(E) eventually
答案是說要選D，但我覺得A應該也可以啊，請問一下為啥A不行？

jointly的話 問題變成"(兩者)是否都有影響" 句子後半應該是直接交代其一"無"影響才切題 但實際上後半是就影響程度來回應 所以推測前面應該也是程度上的主張才合理(equal:兩者都有 程度一樣)