Although the Intent of Informed Consent Is to Provide Participants

Although the intent of informed consent is to provide participants with complete information about a research study before they agree to participate,often this is impossible because

A) deception is an important part of the research.
B) sometimes researchers do not know exactly what will happen in the study.
C) if participants knew the true purpose of the study they might produce artificial behavior.
D) the other three choices are all reasons that informed consent is impossible.