A population of lizards lived in an ecosystem that was prone to flooding. After many generations, most of the lizards in the population had longer legs than their ancestors, which helped them flee from floods. Which statement best explains this change?

A: the lizard genes spontaneously mutated to address the flooding threat

B: Genetic variation among lizard limbs allowed for natural selection to occur

C: The limbs were artificially selected because humans probably caused the flooding

D: The lizards with longer limbs cloned themselves, ensuring survival of the species
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