40. No two people are genetically identical, except for identical twins. The main source of genetic variation among humans is _____
(A) genetic drift
(B) environmental effects
(C) new mutations that occurred in the preceding generation
(D) the reshuffling of alleles in sexual reproduction
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統計: A(0), B(0), C(0), D(5), E(0) #3411524
統計: A(0), B(0), C(0), D(5), E(0) #3411524