Which One of the Following Alternatives Best Illustrates Action Research

Which one of the following alternatives best illustrates action research?

A) A university professor and two of her graduate students conduct systematic observations of kindergarten's turn-taking behaviors on the playground.
B) A middle school math teacher gives his students quizzes every Friday because he knows that frequent quizzes will encourage students to study regularly.
C) After a first-grade teacher completes a research project for her master's thesis, she presents her findings at a national teaching conference.
D) A high school principal conducts a survey to find out what kinds of after-school activities students would most like to have available at their school.