Researchers must important concepts in their studies so others would have a clear understanding of exactly how those concepts were defined.
randomly assign
randomly select
operationalize
generalize

operationalize

Explanation:

Operationalizing is a word that means preparing something that must complete a task. Based on this concept, we can conclude that researchers should operationalize the important concepts in their studies so that others have a clear understanding of how these concepts were defined.

This is because a scientific research is something that is available to the analysis of all people and not everyone knows the scientific concepts related to research, therefore, the scientific concepts must be operationalized, ie prepared; so that all people can understand.

more than 1 person for sure

a is the final ! : )