Philip Zimbardo conducted the Stanford prison experiment in order to test the effects of social roles on behavior. Option B is correct.
Philip George Zimbardo is an American psychologist and a professor emeritus at Stanford University. He became famous as a result of 1971 Stanford prison experiment and has since wrote many introductory psychology books, textbooks for college students, along with other important works, such as The Lucifer Effect, The Time Paradox, and The Time Cure. He is also the founder and president of the Heroic Imagination Project.