"Surprising" Phenomenon
How could the 2009 analysis have detected cobalt and proceeded to suggest that the painting was produced before 1804 while the presence of cobalt led the 1955 analysis to date the painting to post-1804?
Objective
The right answer will describe a difference between the 2009 and the 1955 analyses. That difference must show why, unlike the 1955 analysis, the 2009 study determined that the presence of cobalt does not mean that the painting had to be produced after 1804.
A
The 2009 analysis revealed that cobalt was located only in the topmost paint layer, which was possibly applied to conceal damage to original paint layers.
This shows how the 2009 analysis differed from the 1955 analysis: the 2009 analysis revealed that there was no cobalt in the lower paint layers, so the original work could have been produced before 1804. The topmost layer—the layer containing cobalt—could have been added later.
B
The 2009 analysis used sophisticated scientific equipment that can detect much smaller amounts of cobalt than could the equipment used for the 1955 analysis.
This difference between the analyses doesn’t help explain why the studies led to different conclusions about the painting’s production date. It doesn’t matter how much cobalt the analyses found, just that they both detected some amount and still reached different conclusions.
C
The 2009 analysis took more samples from the painting than the 1955 analysis did, though those samples were smaller.
This provides a difference between the analyses, but it’s not a difference that helps explain why they led to different conclusions about the painting’s production date. The sample sizes and quantities don’t tell us anything about the presence of cobalt or its implications.
D
Many experts, based on the style and the subject matter of the painting, have dated the painting to the 1700s.
This isn’t relevant information. We’re trying to figure out why there’s a discrepancy between the conclusions of the 2009 and 1955 analyses, not when the painting was actually created or what other people think.
E
New information that came to light in the 1990s suggested that cobalt blue was used only rarely in Italy in the years immediately following 1804.
This doesn’t help us understand how the 2009 study and the 1955 study reached different conclusions about the painting’s production date. It doesn’t matter to us whether cobalt was used all the time or only rarely in the years immediately following 1804!
Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that a public health campaign against influenza was heeded by the public. This is based on an observation that the duration of the public health campaign correlated with a much lower rate of influenza than had been predicted.
Notable Assumptions
The author assumes that there is no alternative explanation for the lower influenza rates that simply coincided with the public health campaign.
The author also assumes that the measures encouraged by the campaign are effective against the spread of influenza, so that the public’s following of those measures could cause the lower rates.
The author also assumes that the measures encouraged by the campaign are effective against the spread of influenza, so that the public’s following of those measures could cause the lower rates.
A
The incidence of food-borne illnesses, which can be effectively controlled by frequent hand washing, was markedly lower than usual during the six-month period.
This strengthens by providing further evidence that hand-washing rates were higher during the six-month period. This makes it more likely that during this time period, the public was actually heeding the campaign, which encouraged hand-washing.
B
During the six-month period, the incidence of the common cold, which has many of the same symptoms as influenza, was about the same as usual.
This might actually weaken, since the spread of the common cold would probably also be limited by the measures encouraged by the public health campaign. So if common cold rates were not lower, the campaign may not have caused the lower influenza rates.
C
There were fewer large public gatherings than usual during the six-month period.
It’s not clear without more information whether this is connected to the public health campaign, so it doesn’t help us. This might be due to the campaign’s advice to avoid gatherings when ill, but it could also be unrelated—we can’t jump to either assumption.
D
Independently of the public health campaign, the news media spread the message that one’s risk of contracting influenza can be lessened by frequent hand washing.
This weakens by providing an alternative explanation for the reduction of influenza rates: instead of heeding the public health campaign itself, the public may have just been listening to the news media’s reports.
E
In a survey completed before the campaign began, many people admitted that they should do more to limit the spread of influenza.
This is irrelevant, since the public’s desire to limit the spread of influenza does not provide evidence that they followed the instructions of the public health campaign later on.