# Why is E incorrect?

Recent research indicates that mercury levels in the bodies of saltwater fish are higher now than they were a hundred years ago. Mercury from the fish accumulates in the base of the feathers of seabirds that eat saltwater fish. Feathers taken from seabirds stuffed and preserved in the 1900s were found to contain only half as much mercury as do feathers recently taken from living birds of the same species.
The argument depends on the assumption that
a) The number of sources of pollutants in 1990s was much lower than it is now
b) The quantity of mercury found in the body of a saltwater fish depends on the amount of pollution in the ocean habitat of the fish.
c) The Same techniques used today were used to stuff and preserve birds in the 1900s.
d) The process used to preserve birds in the 1900s did not substantially decrease the amount of mercury in the birds’ feathers.
e) The Proportion of saltwater fish in the diet of seabirds has remained the same since the 1900s.
OA is D
Beginner Asked on March 6, 2018 in

If in option E,  seabirds eat more fishes than 1900s then the Hg content will go up.

D is also correct.

Beginner Answered on March 6, 2018.

Hi Siddhant,

The conclusion here is that mercury levels in the bodies of saltwater fish are higher now than they were a hundred years ago.

Premises: Mercury in feathers taken from seabirds stuffed and preserved in the 1900s  = half of mercury in feathers recently taken from living birds of the same species.

Remember this common pattern in assumption based questions. Whenever the author says X is the reason for Y, look for an alternate reason for Y in  the negated version of the answer choice.

Here X = Mercury in feathers taken from seabirds stuffed and preserved in the 1900s  = half of mercury in feathers recently taken from living birds of the same species.

Y = mercury levels in the bodies of saltwater fish are higher now than they were a hundred years ago

Option D on negating says “The process used to preserve birds in the 1900s substantially decreased the amount of mercury in the birds’ feathers”. This negated version gives an alternate reason for Y (mercury levels rising)

In option E, there is ambiguity. The proportion could have gone up/down.

Expert Answered on March 8, 2018.

For the comparison to be made, the total consumption of fish must remain same. So, if the option E talked about total consumption of fish remaining the same, I think, E would be correct as well.

Either increase in total consumption of fish or decrease in total consumption of fish can result in constant proportion. But what is desired for comparison is constant total consumption.