Answer:
4. Demand characteristics.
Step-by-step explanation:
Demand characteristics refer to the situation where the subject of study change their behaviour according to what they think the experiment is about.
On the other hand experimenter bias, happens when the expertise of the experiment conducts the subject of the study indirectly. Volunteer bias, is thought to happen when there are volunteers on a study, who might have a different behaviour to the entire target group.
