A six-month public health campaign sought to limit the spread of influenza by encouragin people to take precautions s...

Ravi on January 7, 2019

@Boram,

Great question. Let's take a look at this question to see why the answer is A.

The conclusion of the argument is that the public evidently heeded the
campaign, and the support given is that influenza rates when down
during the six-month public health campaign. This is a classic
correlative premise with a causal conclusion (hypothesis).

The question asks us to select an answer that would most strengthen
the argument. In these types of arguments, there are a number of ways
in which we can strengthen. We can block alternative hypotheses or we
could assume the hypothesis is true. If we assume the hypothesis is
true, then it would make certain predictions. Then we'd look for
verifications of these predictions.

Let's assume that the author's conclusion/hypothesis is true: the
public heeded the campaign. If this were true, then that means the
public took precautions such as washing their hands frequently and
avoiding public places when they had influenza symptoms. And if this
were true, a prediction that would come out of this is that whatever
other illness that could be prevented by frequent handwashing would
also be reduced. This is what answer choice A picks up on, and it's
why A is correct.

A says the incidence of food-borne illness, which can be effectively
controlled by frequent hand washing, was markedly lower than usual
during the six-month period. If we assume that the author's hypothesis
is true, then we would expect that frequent handwashing would diminish
the incidence of food-borne illness since food-borne illness can be
controlled by frequent handwashing. This is what A says. In doing so,
it adds further support to the hypothesis that the public listened to
the campaign and started washing their hands more.

Answer B is incorrect because it does nothing to strengthen or weaken
the argument. We have no idea whether occurrences of the common cold
can be reduced by the same activities that the campaign promoted.

Answer C is incorrect because it introduces an alternative cause for
why the incidences of influenza reduced during the period. If this
were true, it would actually weaken the argument.

Answer D is incorrect because it introduces an alternative cause for
the public's change in behavior. If news media spread the message that
more handwashing reduced the risk of influenza, and they spread this
independently of the campaign, then how do we know the public heeded
the campaign? This answer also weakens the argument.

Answer E is incorrect because whether people think they should do
something and whether or not they actually do the action is another
question. This doesn't tell us if these people actually changed their
behavior, so it doesn't do anything for us. We can get rid of this
answer choice.

Does this make sense? Let us know if you have any more questions!