A clinical research unit presents the following bar chart data on the efficacy of three different antihypertensive drugs (Drug X, Drug Y, Drug Z) and a Placebo, measured by the average reduction in systolic blood pressure (SBP) after 8 weeks. The results are: Placebo: 2 mmHg reduction; Drug X: 8 mmHg reduction; Drug Y: 15 mmHg reduction; Drug Z: 9 mmHg reduction. Which conclusion is best supported by this data?
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A
All three drugs are more effective than the placebo, but Drug Y is markedly more effective than Drugs X and Z.
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B
All three active drugs have a roughly equivalent therapeutic effect on systolic blood pressure.
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C
Only Drug Y is effective, as the reductions for Drugs X and Z are too small to be clinically significant.
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D
The placebo effect is so strong that none of the drugs can be considered truly effective.