Critical Reasoning (CR) | Re: The Bluetail Moonbeam, endemic to the streams and rivers of Asia, is

Official Explanation Magoosh:

We import this fish, the Bluetail Moonbeam, and there's the threat of an infectious virus. We want to prevent infected fish from getting into the domestic stocks of these fish and spreading the illness. We can test for antibodies, but the problem is: it takes four weeks from the time of initial infection for enough antibodies to show up in the blood --- before that, the antibody test just doesn't work. Even if we tested each and every fish, some of them might still
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