Placebo Effects Occur When

Placebo effects occur when

A) people's expectations lead them to experience some change, even though they receive a fake or ineffective treatment.
B) people recover from a mental or physical illness without any form of intervention.
C) people who originally score extremely high or low on some trait are measured a second time, and their new score falls closer to the average.
D) people who originally score near the average on some trait are measured a second time, and their new score falls at the extreme high or low end of the scale.