If a trait becomes more common in a small population only by chance, why may it be wrong to call it natural selection?
Natural selection involves consistent differences in survival or reproduction associated with heritable traits, usually because those traits are advantageous under particular conditions. In contrast, genetic drift changes allele frequencies through random sampling or chance, with no requirement that the increasing trait be useful. Thus A is correct. Small populations do have genes, and B, C, and D are false generalisations.
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