Harley1980 wrote:
Naturalist: For several years, coyote have had a robust population throughout the Susquehanna National Forest. Over the past seven years, the Canic Chemical Corporation in nearby Harrisville has been releasing low levels of bromide compounds into the air and groundwater. Some of these compounds, in sufficient concentrations, are suspected of compromising the immune systems of young coyote. A recent study over the entire forest established that 30% of young coyote did not survive their first year of life. Clearly, the bromide compounds released by Canic pose a direct threat to the well-being of coyote in the forest.
The answer to which of the following would be most useful for evaluating the naturalist's reasoning?
A) Have significant levels of these bromide compounds been measured in the blood of other mammals in the forest?
B) To what parts of the forest does the wind carry the particulate form of these bromide compounds?
C) How many of the natural springs in the forest derive from groundwater that flows in the vicinity of Harrisville?
D) What naturally available nutrients would strengthen the immune system of young coyote against any effects of these bromide compounds?
E) What percentage of healthy coyote survive to adulthood in the wild?
For several years, coyote have had a robust population.
(doesn't say population has declined now)Over the past 7 years, CCC has been releasing low levels of bromide compounds into the air and groundwater.
(note, low levels)Some of these compounds, in sufficient concentrations, are suspected of compromising the immune systems of young coyote.
(note, in sufficient concentrations)A recent study over the entire forest established that 30% of young coyote did not survive their first year of life.
Conclusion: the bromide compounds released by Canic pose a direct threat to the well-being of coyote in the forest.
The argument doesn't say that the population is reducing. It suspects that sufficient concentration could reduce immunity of young. Then we are told that 30% of the young do not survive. But here is the important question - what does this 30% mean? Is it a number of concern? What if 30% coyote young do not survive naturally too? Then the chemicals may not be a problem. What if only 5% coyote young die of natural causes? Then it seems too many are dying and something (perhaps the chemicals) is at play here.
To evaluate the conclusion, we need to know what percentage of young survive naturally (without the chemicals in their environment). Animals give birth in litters and often only a fraction of their young survive. We need to know what that fraction is for coyotes.
Option (E) What percentage of healthy coyote survive to adulthood in the wild?
Gives us what we were looking for. If 95% healthy coyote survive to adulthood in the wild, then the chemicals seem to be a threat.
If 70% healthy coyote survive to adulthood in the wild, then the chemicals seem to be harmless.
I actually just glazed over the other options since what I was looking for was obvious. Had I not found it, I would have evaluated other options in this way:
A) Have significant levels of these bromide compounds been measured in the blood of other mammals in the forest?
Other animals are out of scope.
B) To what parts of the forest does the wind carry the particulate form of these bromide compounds?
Coyotes live throughout the forest. So this is irrelevant.
C) How many of the natural springs in the forest derive from groundwater that flows in the vicinity of Harrisville?
We don't know what this implies. We are given that the groundwater is contaminated. How many springs are there? Does flowing in the vicinity mean contamination but not otherwise? What if the contaminants percolate to all the groundwater? Which springs do coyotes use, if at all? There are too many unknowns to make any sense.
D) What naturally available nutrients would strengthen the immune system of young coyote against any effects of these bromide compounds?
Out of scope.
Answer (E)
_________________
Karishma Bansal - ANA PREP
*SUPER SUNDAYS!* - FREE Access to ALL Resources EVERY Sunday
REGISTER at ANA PREP
(Includes access to Study Modules, Concept Videos, Practice Questions and LIVE Classes)
YouTube Channel
youtube.com/karishma.anaprep