medium · GMAT Verbal

Which of the following is an assumption required by the argument?

1. Among every available preventive measure, frequent hand-washing is the single most important factor in stopping the spread of all infections.
2. During the trial period, the hospital staff were not aware that they were being monitored for their compliance with the new hygiene protocol.
3. The decline in infections was not caused by other factors, such as a change in the types of patients admitted or a seasonal decrease in viral activity.
4. The reported rise in hand-washing compliance was sustained at the same high level throughout the entire period during which infection rates were tracked and measured.
5. Before the protocol was introduced, the hospital's overall infection rates had ranked among the highest of any facility anywhere in the surrounding region.

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