The Main Point of the Rosenhan Article "On Being Sane

The main point of the Rosenhan article "On Being Sane in Insane Places" is:

A) most mental illnesses have environmental causes
B) psychiatric nurses have better medical and interpersonal skills than psychiatrists
C) psychiatrists cannot accurately distinguish between the sane and the mentally ill
D) the setting in which behavior occurs has little influence on people's perceptions
E) there is a strong relationship between mental illness and social class