Which of the following is true about the ethical conduct of psychological research?

Which of the following is true about the ethical conduct of psychological research?
 
  a. It is good scientific procedure to tell participants about the research hypotheses before they participate.
  b. If research participants are misled about a study, they must be fully debriefed at the end of the study.
  c. Darley and Latan could have easily tested their hypotheses about helping behavior by telling participants in advance that they would hear someone pretending to have a seizure.
  d. It is never permissible to use deception.