<p>This is actually a <span style="color:#8e44ad;"><strong>Critical Reasoning</strong></span> question, as indicated by the phrase "if true". Specifically, it seems similar to an <span style="color:#8e44ad;"><strong>Explain the Paradox</strong></span> question, given the phrase "would make the information presented in the passage". Whilst the question isn't explicitly of this type, we can still employ the same approach.</p>
<p>Step 1: Identify the TWO CONTRADICTORY STATEMENTS.</p>
<ul>
<li>The flood should have caused the native fish population to be flushed down the river.</li>
<li>The nets placed to catch fish being flushed down the river didn't catch much more fish during the flood.</li>
</ul>
<p>Step 2: BUILD A BRIDGE to provide a new piece of information to make the paradox disappear</p>
<ul>
<li>We need some explanation that ensures both of the statements above hold true. Most likely it should be something suggesting that the nets did not catch a lot of the excess fish that were "flushed" downstream.</li>
</ul>
<p><span style="color:#27ae60;"><span style="font-size:20px;">The Right Answer</span></span></p>
<p><span style="color:#27ae60;">A:</span> This explains why the flooding could have caused flushing, but also why more fish were not caught in the nets. The fish would have flowed straight through the net!</p>
<p><span style="color:#e74c3c;"><span style="font-size:20px;">The Wrong Answers</span></span></p>
<ul>
<li><span style="color:#e74c3c;">B:</span> This actually increases the paradox. If the native fish population had gone up before the flood, surely more should have been caught in the nets.</li>
<li><span style="color:#e74c3c;">C:</span> This does nothing to resolve the paradox. The native fish being better swimmers does not explain why they were not caught in the net.</li>
<li><span style="color:#e74c3c;">D:</span> This does nothing to resolve the paradox. The question is about native fish, not the trout, which was "nonnative" according to the passage.</li>
<li><span style="color:#e74c3c;">E:</span> This does nothing to resolve the paradox. We do not know anything about how water level affects the flood or the flushing of fish.</li>
</ul>