PP1 (Shorter) Verbal Section 2 (Medium) Q14
This is actually a Critical Reasoning question, as indicated by the phrase "if true". Specifically, it seems similar to an Explain the Paradox 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.
Step 1: Identify the TWO CONTRADICTORY STATEMENTS.
The flood should have caused the native fish population to be flushed down the river.
The nets placed to catch fish being flushed down the river didn't catch much more fish during the flood.
Step 2: BUILD A BRIDGE to provide a new piece of information to make the paradox disappear
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.
The Right Answer
A: 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!
The Wrong Answers
B: 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.
C: This does nothing to resolve the paradox. The native fish being better swimmers does not explain why they were not caught in the net.
D: This does nothing to resolve the paradox. The question is about native fish, not the trout, which was "nonnative" according to the passage.
E: This does nothing to resolve the paradox. We do not know anything about how water level affects the flood or the flushing of fish.