If deception is necessary in research, according to the Ethical Principles of Psychologists and Code of Conduct, psychologists must explain the deception no later than:a. at the conclusion of data collection b. at the conclusion of a participant's participation c. during Informed Consent before the start of the study d. deception is never allowed

a. at the conclusion of data collection

Explanation:

According to Section 8.07 of Ethical Principles of Psychologists and Code of Conduct of the American Psychological Association, Psychologists are not to use deception in research unless the study unless it is not possible to use non-deceptive alternative procedures.

When deception is used, the APA recommends that the participant is told as early as possible of the deception with that being as soon as the participant is no longer participating and failing that, no later than at the conclusion of data collection. Participants are also allowed to decline the use of their data after they discover the deception.