What Does the Hawthorne Effect Refer To

What does the Hawthorne effect refer to?

A) Research that takes place in a natural setting
B) Research that takes place in an artificial setting
C) A treatment that has no effect in an experiment.
D) The effect that occurs when a researcher measures the dependent variable measure such that all the subjects get a perfect,or near perfect score.It means that by random chance alone the scores are likely to be lower the next time the same subjects are measured.
E) A situation in which subjects react to the fact that they are in an experiment more than they react to the treatment