A team of public health researchers hypothesizes that installing free handwashing stations in schools reduces absenteeism due to illness among elementary students.
Which finding, if true, would most strongly support the team's hypothesis?
- A
Teachers report that handwashing stations are popular with students.
- Bcheck_circle
Schools that installed handwashing stations saw a 30 percent decrease in illness-related absences over a school year, while schools without stations saw no change.
- C
Most students wash their hands without prompting after using the bathroom.
- D
Handwashing stations are less expensive to maintain than disposable hand sanitizer dispensers.
Explanation
A directly compares absenteeism before and after the intervention with a control, establishing the predicted effect. B, C, and D are tangential to the hypothesis.