A Major Disadvantage of Using Laboratory Observation in a Research

A major disadvantage of using laboratory observation in a research study is that:

A) the presence of researchers may cause participants to act differently than they would in their natural surroundings.
B) it can be used only for explaining behaviour and not for describing it.
C) it is often considered unethical.
D) researchers have less control of the situation than they do in a naturalistic observation.