Self-study
Support In 1988, a significant percentage of seals in the Baltic Sea died from viral diseases; off the coast of Scotland, however, the death rate due to viral diseases was approximately half what it was for the Baltic seals. ███ ██████ █████ ███ █████████████ ██████ ██████ ██ ██████████ ██ █████ █████ ████ ███ ███ ████████ ██████ █████ ██████████ ███ █████ ██ ██████ ██████ ████████ ███████ ██ █████ ███ █████ ██████████ ██ ██ ██████ ████ ███ ██████ █████ ████ █████ ███ ██████ █████ ███ ███ ██ ███ ██████ ██████ ██ ██████████ ██ █████ ██████
Argument Breakdown
The stimulus tells us about seals that died from viral disease in 1988 in the Baltic Sea and off the coast of Scotland. There's a lot of information being thrown at us, so let's break down what we know:
(1) the death rate from the virus for Baltic seals was twice the death rate for Scottish seals; (2) Baltic seals had significantly more pollutants in their blood than Scottish seals; (3) pollutants make marine mammals more vulnerable to viruses.
From all this, the author concludes that pollutants were the likely cause of the Baltic seals' higher death rate. This argument follows a phenomenon-hypothesis structure. The conclusion is a hypothesis meant to explain the phenomenon of the differing death rates between two seal populations.
Objective: Strengthen
There are a few ways we can strengthen a phenomenon-hypothesis argument. One strategy is to eliminate alternative explanations to make the author's hypothesis more likely. For instance, we could say that the same virus affected both groups of seals. Another strategy is to identify corroborating evidence which we would expect to see if the hypothesis were true. For example, if viral death rates in other groups of seals were also correlated with higher pollutant levels, that would be consistent with the hypothesis.
12.
Which one of the following, ██ █████ ████████ ███ ████ ██████████ ███████ ███ ███ █████████
a
The large majority ██ ████████ █████ ████ ████ ████ ██████ ███ ██ █████████ ████████
(A) aligns with our common-sense expectations, but it lacks any link to pollutants, which prevents it from strengthening. (A) doesn't make the hypothesis that pollutant levels made the Baltic seals more vulnerable any more likely.
b
The strain of █████ ████ ██████ ████████ █████ ██████████ ████████ ██████ ███████ ████ ████ ███████ ████ ██ ████ ███████ ██████ ████████
Like (A), (B) is missing a connection to pollutants, which we need to strengthen the hypothesis that pollutants led to the higher death rate in Baltic seals.
c
There were slight ████████████ ██ ███ ██████ ██ ██████████ █████ ██ ███ █████ ██ ██████ ██████
We already know that the Baltic seals had more pollutants in their blood than the Scottish seals—a slight variation in those levels doesn't make a difference to the argument.
d
The kinds of ██████████ █████ ██ ███ ██████ ███ ███ █████████████ █████████ ████ █████ ████ ████ ████ ████████ ██ ███ ██████ ███ ███ █████ ██ █████████
(D) looks promising because it discusses pollutants, but the author is only concerned with the levels of pollutants. (D) introduces a new consideration—the kind of pollutants—that shifts away from the author's concern with pollutant levels.
e
Among marine mammals █████ ████ ██████ ███ █████ ████ ███ ██ █████ ████████ ██ ████ ███ ██████ ██ ███ ██████ ███ ████ ██ ███ ███ ███ ████████ ██████
(E) isn't limited to seals, but still provides corroborating evidence by strengthening the correlation between pollutants in the Baltic Sea and marine mammals' vulnerability to viruses.
The author relies on evidence that pollutants make marine mammals generally more vulnerable to viruses, and (E) links that more closely to the comparison between the Baltic Sea and the waters off the Scottish coast.