Nissan Motor Corporation Sent a Japanese Researcher to Stay at the Home

Nissan Motor Corporation sent a Japanese researcher to stay at the home of a California couple as part of a student exchange program.However,the researcher was really spying on the couple to better understand automobile buying behavior.This illustrates that:

A) all good observations should be covert.
B) observation raises ethical questions.
C) observation is not a good research technique.
D) structured observation is legal.
E) unstructured observation is legal.