Pharmaceutical researchers observed that patients with chronic hypertension who consumed two cups of hibiscus tea daily demonstrated modest reductions in systolic blood pressure. The researchers hypothesized that antioxidant anthocyanins in hibiscus promote endothelial nitric oxide production.

Which of the following is an assumption required by the researchers' hypothesis?

Answer and explanation

Correct answer: B. The reduction in blood pressure was not solely attributable to the increased fluid intake associated with drinking the tea

  1. Step 1: Identify the specific causal hypothesis: researchers propose that antioxidant anthocyanins specifically produce the observed reduction in blood pressure.
  2. Step 2: Apply the assumption framework (necessary condition): rule out plausible rival explanatory factors that were introduced as part of the intervention protocol.
  3. Step 3: For the biochemical action of anthocyanins to be the cause, the reduction in blood pressure must not be solely attributable to the increased fluid intake from drinking two cups of tea daily.
Answer
The reduction in blood pressure was not solely attributable to the increased fluid intake associated with drinking the tea.

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