Bunuel
A research team discovered that a species of genetically modified (GM) salmon had escaped from a nearby aquaculture facility and interbred with wild salmon in a local river system. In the first spawning season after the escape, genetic testing of juvenile wild salmon confirmed the presence of GM genes. The facility was then shut down and all remaining GM salmon were removed. Three years later, a follow-up study that sampled hundreds of wild salmon found no trace of GM genes.
Which of the following, if true, most helps to explain the discrepancy between the two studies?
A. Offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon.
B. Natural predators tend to avoid genetically modified salmon because of differences in their taste.
C. Genetically modified salmon are more likely to escape into ocean environments than remain in rivers.
D. Wild salmon in the river system typically migrate to distant spawning grounds and return only every few years.
E. Fewer than ten adult GM salmon escaped before the facility was closed.
GM genes were found initially in juvenile hybrid salmons.
Disappeared later ----> After 3 years---> No trace of GM genes.
What could be the reason?
A. Offspring of genetically modified and wild salmon had significantly lower survival rates in the river environment than offspring of two wild salmon.
This option explains why there were traces of GM genes found initially and later due to low survival rates, the hybrid ones weren't able to survive and hence no traces were found.
Correct.
B. Natural predators tend to avoid genetically modified salmon because of differences in their taste.
This contradicts the situation. The GM salmons would survive better in this case.
Incorrect.
C. Genetically modified salmon are more likely to escape into ocean environments than remain in rivers.
The argument is about the offspring and not the adult GM, which later migrated.
Incorrect.
D. Wild salmon in the river system typically migrate to distant spawning grounds and return only every few years.
Still doesn't explain no trace of GM genes. There could've have been some trace of GM genes in this case.
Incorrect.
E. Fewer than ten adult GM salmon escaped before the facility was closed.
Still they can breed and GM genes can be found.
Incorrect.
ANSWER: A