A multistage sample design was selected.
Answer: Option E.
Explanation:
In statistics, multistage sampling is the taking of tests in stages utilizing littler and littler examining units at each stage. Multistage examining can be an unpredictable type of bunch testing since it is a sort of inspecting which includes partitioning the populace into gatherings.
Multistage sampling divides enormous populaces into stages to make the inspecting procedure increasingly handy. Rather, you partition the populace into states and take a basic irregular example of states. For the following stage, you may take a basic irregular example of schools from inside those states.