Of the Following,which Is the Best Example of a Naturalistic

Of the following,which is the best example of a naturalistic observation?

A) A serial killer is subjected to a battery of psychological exams and intensive interviews in an effort to determine the factors that influenced his developmental pathway to homicidal behaviour.
B) A researcher interested in the effects of caffeine on learning provides high-caffeine drinks to an experimental group who are being taught a complicated game and caffeine-free drinks to a control group who are being taught the same game.
C) Researchers interested in children's gender-related interactions videotape children while they are playing during recess and while they are engaged in cooperative learning assignments in their classrooms.
D) A researcher is studying the effects of sleep deprivation on 20-year-olds in a sleep lab.