Explanation
Correct answer: D.
Choice D is the best answer because it most effectively uses data from the table to complete the statement comparing the mean ratings for two different groups of participants in a study. The text explains that a research team evaluated the study's participants using various measures in order to learn whether there might be a medical benefit to telling patients they're receiving a placebo. The table shows the team's mean ratings for participants after 21 days for three of the measures: global improvement, symptom severity reduction, and quality of life improvement. According to the table, the mean ratings were higher for all three measures for participants aware of taking a placebo than for participants in the control group. Given that higher ratings indicate greater well-being, as the text states, the mean ratings in the table indicate greater overall well-being for participants aware of taking a placebo than for participants in the control group.
Why the other choices are wrong
Choice A
Choice A is incorrect because the table doesn't include data about individual participants; rather, it presents means, or mathematical averages, of ratings. For this reason, no conclusions can be drawn from data in the table about the extent to which well-being may have varied from participant to participant.
Choice B
Choice B is incorrect because according to the table, the mean ratings for participants aware of taking a placebo were higher for all three measures than for participants in the control group, not lower for two of the measures.
Choice C
Choice C is incorrect because it cites data from the table related to participants in the control group, not to participants aware of taking a placebo. Additionally, the mean ratings in the table for participants aware of taking a placebo are higher for all three measures than for participants in the control group. Given that higher ratings indicate greater well-being, as the text states, the ratings in the table for participants aware of taking a placebo indicate greater well-being for these participants in all three measures.