Which One of the Following Is the Best Example of Action

Which one of the following is the best example of action research?

A) A teacher gives her students a questionnaire that asks them to describe how often they study and what kinds of strategies they use when they study. She will use the results to develop several lessons on effective study skills.
B) A graduate student quietly observes adolescents' behaviors in the school cafeteria. He plans to describe his observations in his master's thesis.
C) A college professor recruits sixth graders to come to his lab, where she assesses their responses and reaction times in a variety of challenging problem-solving tasks. Her results will help her refine her theory about the development of children's problem-solving skills.
D) All of the school districts in a particular state are instructed to give the same mathematics achievement test to all eleventh graders. The average test scores for each district will be presented in a report that will be released to the general public.