Seth, a Psychologist, Would Like to Conduct Research in the Form

Seth, a psychologist, would like to conduct research in the form of naturalistic observation of drug sales and use among teenagers in his 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) His sample is insufficiently representative for naturalistic observation.
D) Study participants tend to want to appear socially appropriate.