In 1996, scientists caused an experimental flood of the Colorado River by releasing water from Glen Canyon Dam above the Grand Canyon. Because an unintentional flood in 1983 had reduced the river’s introduced population of nonnative trout, biologists were concerned that the experimental flood would wash many fish, native and nonnative,downstream. To find out, biologists placed nets in the river. The nets captured a few more trout than they would have without the flood but did not show substantial flushing of native fish, whose ancestors had, after all, survived many larger natural floods. The biologists surmised that the native species(and most of the trout) must have quickly retreated to protected areas along the riverbank.[/box_in][box_in]Which of the following, if true, would make the information presented in the passage compatible with the experimental flood’s, in fact, having caused substantial flushing of native fish?

A) Many of the native fish are too small to have, been captured by the nets.
If there are many of the fishes small enough not to be caught by nets, there is a possibility that there were lot of fishes that were actually washed off but very few were caught in the nets.
Perfectly matches

B) There had been an increase from normal levels in the native fish population prior to the flood.
I would say it gives a reason to think otherwise. If there were an increase in the number, that would say that actually whatever little increase was there was due to the increased number
In other words, the flood did not have any effect at all.

C) The native fish in the Colorado are much stronger swimmers than taxonomically similar fish in other rivers in the region.
We are not concerned with other rivers

D) The unintentional flood of 1983 had not affected the river’s trout population as much as was originally thought.
Does not affect the point under consideration

E) The experimental flood raised the water level much less than a typical natural flood would have.
We are talking just about the effect of experimental flood.
Does not affect the point under consideration

A is correct





Consider all that apply
The line that affects our answer is -


According to the passage, which of the following is true of the Colorado River flood of 1983?

A) The flood had a negative effect on the river’s trout population.
reduced the river’s introduced population of nonnative trout-So there is a negative effect on the population as here we are not concerned about native or non-native, we are concerned about overall effect
Overall the population has gone down due to flood.. So correct

B) There was substantial flushing of the river’s native fish population during the flood.
No mention of this

C) Unlike the 1996 flood, it was not deliberately caused for scientific research purposes.
an unintentional flood in 1983- this clearly tells us that it was not deliberately caused
So, correct

Show: :: OA

C

OA cannot be just C, it will have to be A and C.