If a disease wiped out the hare population, then result would be :
<u>The </u><u>arctic fox</u><u> population could </u><u>decrease</u><u> because they would </u><u>lose</u><u> a </u><u>food source</u><u>.</u>
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It cannot be A because although the arctic fox population might decrease, it would only cause an increase in its prey's population as there are less predators (arctic fox) to consume it.