Participants were asked to rate the importance of achieving honor-roll status. Researchers found that students from smaller families rated the importance more highly than students from larger families. The research team concluded that a student’s attitude toward school achievement is the result of family size. Which of the following is the most important error made by the research team? (A) Perceiving order in random events (B) Generalizing from extreme examples (C) Using self-report data (D) Failing to randomly assign participants to conditions (E) Assuming that correlation proves causation