3. Consider this study on social stress conducted by Kim Mooney (1990) at the University of New Hampshire. SBP was measured at six points in time using a Finapres noninvasive blood pressure monitor: Time 1: When participants arrived at the laboratory and before they signed an informed consent form Time 2: After participants read and signed an informed consent form that told them that they would be doing a stressful social role play (about being accused of shoplifting) that would be videotaped (they were told that they had 5 minutes to think about what they would say in this situation) Time 3: After a 5-min period (during which they prepared what to say) Time 4: During the stressful social role play Time 5: Ten minutes after the role play was completed Time 6: Twenty minutes after the role play was completed At each point in time, for each of 65 participants, SBP was measured; the variables sys1, sys2, ..., sys6 correspond to the measurements of blood pressure made at the six points in time just described. (The blood pressure monitor used in this study looked at peripheral arterial pressure in the middle finger, and so the blood pressure readings tended to be systematically higher than the readings usually obtained by more conventional blood pressure measurement methods.)

The repeated-measures variable in this experiment is: a. Social stress b. Time c. Blood pressure d. None of these options