To Test the Efficacy of Vitamin C in Preventing Colds

question 21

Multiple Choice

To test the efficacy of vitamin C in preventing colds, army recruits are randomly assigned to one of two groups: one in which 500 mg of vitamin C is administered daily, and one in which 500 mg of a placebo is administered daily. Both groups are followed to determine the number and severity of subsequent colds. Which of the following study designs most appropriately characterizes this situation?

• A) Cross-sectional study
• B) Case-control study
• C) Prospective cohort study
• D) Historical prospective cohort study
• E) Clinical trial

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