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?