The four sentence (S1 to S4) paragraph below, Sentences S1 and S4 are given. From the options P, Q, R and S, choose the appropriate sentences for this respectively: (Sentence Arrangement) S1. Placebos are essential to the design of reliable clinical trials. S2. S3. S4. Red, Yellow and orange are associated with a stimulant effect, while blue and green are related to tranquilizing effect; says Dr. A. J. de Craen. 1. Such studies have found that even the color of pills made a difference in placebo results. 2. Their once-surprising effect on participants has become the focus of many studies. 3. Another argument says that by prescribing a placebo to placate a patient, the correct Diagnosis of a serious ailment might be postponed 4. At one time, placebos were only used in experiments as a control