In the 1950s, a fungus nearly wiped out an entire species of bananas that were produced through cloning.

Cloning produces bananas that are genetically very similar, so they have little genetic variation. If a fungus can infect one banana, it can often infect the others as well, allowing the disease to spread through the crop. Choice A, the bananas had a lack of genetic variation, explains why the species was so vulnerable.

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