Earthworms are known to secrete a slimy mucus that pervades gardens and farms as they move through dirt and soil. To learn more about how this mucous affects crop yields on farms, scientists compared farms with thriving earthworm populations to farms where earthworms are absent or were only reintroduced recently. Finding that farms with larger earthworm populations tended to have better yields and healthier crops than those without earthworms, it was hypothesized that the slimy mucus improves fertilizer efficiency, which in turn creates healthier crops and greater farm output.Which finding, if true, would most directly undermine the hypothesis?At some farms in the study, soil that contained large earthworm populations contained more nutrients that are associated with plant growth.eliminateAt several non-farming sites not included in the study, there are large, well-established earthworm populations with few plants growing.eliminateAt several farms not included in the study, the abundance of nutrients in the soil correlates negatively with the size of earthworm populations. eliminateAt some farms in the study, the health of animals unrelated to the crops correlates negatively with the size of earthworm populations.