Use the Following to Answer Questions

Use the following to answer questions :
Scenario I
The scenario is based on and presents fabricated data consistent with the following study:
Merikle,P.M. ,& Skanes,H.E.(1992) .Subliminal self-help audiotapes: A search for placebo effects.Journal of Applied Psychology,77(5) ,772-776.doi:10.1037/0021-9010.77.5.772
Merikle and Skanes (1992) investigated the effectiveness of subliminal self-help audiotapes to promote weight loss in overweight females seeking to lose weight.Participants were randomly assigned to groups.Participants in two groups were instructed to listen to audiotapes containing subliminal messages associated with weight loss daily.Group 1 (the subliminal group) actually received these tapes.Group 2 (the placebo group) received tapes containing subliminal messages associated with relieving dental anxiety.Finally,a third group of participants was not given audiotapes and was told that they were on a waiting list to participate in the study.All participants-including the participants on the waiting list-were weighed weekly for 5 weeks.The average total weight loss (and standard deviations) for the three groups after the fifth week is presented in Figure 5.1.
Figure 5.1
-(Scenario I) If subliminal messages truly are effective at promoting weight loss,then:

A) participants in the subliminal group should lose more weight than those in the other two groups.
B) only those participants in the subliminal group should lose weight.
C) participants in the subliminal and placebo groups should lose approximately the same amount of weight.
D) there must be no difference in weight loss between the placebo and waiting-list groups.