Final answer:
The correct answer is d. naïve subject. A naïve subject is an actual participant who agrees to participate in a research study but is unaware that deception is being used to conceal the real purpose of the experiment.
Step-by-step explanation:
The correct answer to the question is d. naïve subject.
A naïve subject is an actual participant who agrees to participate in a research study but is unaware that deception is being used to conceal the real purpose of the experiment. In research, the term 'naïve subject' is used to differentiate these participants from confederates or actors who are aware of the experiment and work for the researcher.