Participants Are Told They Will Be Compensated 10 Pounds for Completing

Participants are told they will be compensated 10 pounds for completing a one-hour study on describing traumatic experiences. They are told in the consent form that it will take one-hour. Thirty minutes into the study a participant says that they wish to stop. You should:

A) tell them that they consented to a one-hour study and that they must stay in the room, but they do not have to continue with the task.
B) thank them for taking part, allow them to leave, but not compensate them because they did not complete the task.
C) thank them for taking part, allow them to leave, and give them five pounds compensation for the time they spent.
D) thank them for taking part, allow them to leave, and give them ten pounds compensation.