The flu is spread every 30-45 years since the 16th century, so we know when to prepare and how to do it. Also, we have learned where it will strike and the containment. Hope this helps! :)
Answer:
Intervention study
Explanation:
An intervention study is a type of controlled clinical trial in which an intervention is applied to a group of people and the outcome is compared to a similar group without the intervention. An example of this type of study is shown in the question above, where a margarine which vegetable ingredients (which is the intervention) will be given to a group of people, so that their blood cholesterol levels are compared to the cholesterol levels of a group of people who didn't use this margarine.
D. a solid to liquid hope this helped!
I would say: not sleeping enough
The answer to your question is D.
