An Article You Read Refers to the Hawthorne Effect

An article you read refers to the Hawthorne effect. What does this mean?

A) It is a special instrument for measuring emotionally-charged attitudes invented in the 1930s Hawthorne, England.
B) It is a type of experimental design using three control groups developed by Sir Thomas Hawthorne in the 1960s, when investigating the effects of noise on mental concentration.
C) It is what happens when the researcher uses a two-way mirror in research to observe people without them being aware of it.
D) It is the effect that occurs when a researcher measures the dependent variable 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) none of the above.