A Valid Reason for Using Deception in Some Behavioral Science

A valid reason for using deception in some behavioral science research is that

A) if participants knew the purpose of the study, they might respond differently and thus invalidate the results.
B) some studies involve aversive experiences, and participants might refuse to participate if they knew this fact.
C) many researchers are interested in the study of how individuals respond to the fact that they have been deceived.
D) it increases the likelihood of significant differences between the experimental and control group participants.