The correct answer is (B):
2 begins the paragraph describing placebo effect and goes on to sate that placebo effect used to be dismissed by researchers as a psychological effect. 5 follows 2 stating that placebo effects are now being studied as a potential portal into the self-healing powers of the body. 4 follows 5 elaborating on the effectiveness of placebo effect in empowering chronic patients to believe in the notion of our bodies' capacity for self-healing. 3 carries forward the discussion stating that the placebo effect is not based only on believing in treatment and that the clinical setting in which treatments are administered is also important. 1 concludes the paragraph reiterating the importance of placebo effect in providing effective treatment. The appropriate sequence is 25431.