GMAT Critical Reasoning (CR) | Re: In the arid land along the Colorado River, use of the

In the arid land along the Colorado River, use of the river's water is strictly controlled: farms along the river each have a limited allocation that they are allowed to use for irrigation. But the trees that grow in narrow strips along the river’s banks also use its water. Clearly, therefore, if farmers were to remove those trees, more water would be available for crop irrigation

Which of the following, if true, most seriously weakens the argument?

Conclusion - Remove trees -> more water
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