The populations of certain species of amphibians have declined dramatically in recent years, an effect many scientist...

Ryan on October 21 at 03:49PM

Why is A correct? Why is C incorrect?

Thanks

2 Replies

Ben on November 13 at 12:15AM

Hi Ryan, thanks for the question!

For necessary assumption questions, we negate the answers we are considering and test whether they will damage the conclusion.

When we negate answer choice A, it takes on the form of the following: The amphibian species whose population declines have been attributed by many scientists to industrial pollution ARE known to be among those species whose population do not vary greatly as a result of natural variations in the weather"

This is a very long way of saying that their populations do not vary greatly due to natural temperature fluctuations.

If this is the case, then it isn't impossible to determine whether this population decline was due to industrial pollution, because we no longer have to consider the impact of temperature fluctuations.

As for answer choice C, why would it be necessary that it cannot be a combination of the two reasons that led to the decline in the amphibian population. This does not have to be true.

Hope this helps!

Friday at 04:03AM

Hi Ben,

Wouldn't the correct negation of "The amphibian species whose population declines have been attributed by many scientists to industrial pollution are not known to be among those species whose populations do not vary greatly as a result of natural variations in the weather," be "The amphibian speciies whose populations declines have been attributed by many scientists to industrial pollution ARE known to be among those species whose populations DO vary greatly as a result of natural variations in the weather?" The negation is suppose to destroy the argument.