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A recent study has shown that, in a certain geographic region, average human body temperature has decreased over the last century at an average rate of 0.05 degrees Fahrenheit per decade. One theory is that this change is due to advances in technology making thermometers more accurate over time. However, comparisons of body temperature data taken with similar thermometers across multiple decades showed the same gradual change. Additionally, the results are consistent across all demographic groups over this time period. In light of these results, researchers now hypothesize that this decrease in average body temperature corresponds to a decrease in average metabolic rate.
Which of the following, if true about this geographic region, would most strengthen the researchers’ hypothesis?
(A) The effect noted in the study is consistent across adults and does not vary according to diet or activity level.
(B) Increased inflammation can increase metabolic rate, and temperature-controlled environments that have become much more prevalent over the last century produce a reduction in inflammation.
(C) Over the past century, increased research into thyroid disorders, such as hyperthyroidism and hypothyroidism, has greatly improved medical science’s understanding of how hormones can influence a person’s metabolism.
(D) In some instances, the researchers conducting the study had to rely on information from other studies and were not able to directly gather the data themselves.
(E) The percentage of adults willing to participate in scientific studies has increased over the last century, as public perception of medical research has changed.
Manhattan Prep Official Explanation:Step 1: Identify the Question The words
strengthen the researchers’ hypothesis indicate that this is a Strengthen the Argument question.
Step 2: Deconstruct the Argument This argument consists of a series of proposed explanations for an observation. Researchers have observed that, over the course of the last century, the average body temperature of people in a certain geographic region has decreased. The researchers show that the difference is not due to use of different thermometers and that the difference is not specific to any particular demographic groups. The researchers’ final hypothesis is stated in the last sentence:
This decrease in average body temperature corresponds to a decrease in average metabolic rate.Step 3: Pause and State the Goal In Strengthen questions, the goal is to find an answer choice that makes the conclusion more likely to be valid. In this instance, the goal is an answer choice that makes it more likely that the decrease in average body temperature over the last century is due to a decrease in average metabolic rate.
Step 4: Work From Wrong to Right(A) This answer choice does not directly address a change in average metabolic rate. It arguably reinforces the premise that
the results are consistent across all demographic groups over this time period. However, reinforcing an already-known premise does not add any new information to support the researchers’ new hypothesis.
(B) CORRECT. If temperature-controlled environments produce a reduction in inflammation, then any results of inflammation should also be reduced. Since increased inflammation increases metabolic rate, a reduction of inflammation would lead to a lower metabolic rate. Finally, if temperature-controlled environments have become much more prevalent in this region over the last century, as this choice states, then this would lend support to the hypothesis that reduced metabolic rate is a factor in the reduction of average body temperature.
(C) This choice addresses thyroid influences on the metabolic rate, but does not give any information as to whether that influence could account for a large-scale change in metabolism over the last century, nor does it provide any connection between thyroid issues and body temperature. Additionally, this choice offers no information about whether thyroid issues have caused any
trend, either upwards or downwards, in metabolic rate.
(D) Absent further information regarding the reliability of these other studies, this choice does nothing to the argument. (Note: While it might be tempting to think this choice casts doubt on the reliability of the information, nothing in the choice actually calls that information into question. This is a Strengthen question, so that distinction doesn’t matter here, but don’t fall into this trap on a Weaken question.)
(E) This choice may indicate that the researchers have more aggregate data in more recent decades, but this does not indicate anything about differences in metabolic rate over the last century.