Mary Jane,a Psychologist,would Like to Conduct Research in the Form

Mary Jane,a psychologist,would like to conduct research in the form of naturalistic observation of marijuana sales and use among teenagers in her city's poorest neighborhood without their knowledge.What problem does this raise?

A) The research may be unethical.
B) People often behave differently when they know they are being observed.
C) Her sample is insufficiently representative for naturalistic observation.
D) Study participants tend to want to appear socially appropriate.