Adesigned experiment is described. identify the specified element of the experiment. in a clinical trial, 780 participants suffering from high blood pressure were randomly assigned to one of three groups. over a one-month period, the first group received a low dosage of an experimental drug, the second group received a high dosage of the drug, and the third group received a placebo. the diastolic blood pressure of each participant was measured at the beginning and at the end of the period and the change in blood pressure was recorded. identify the factor. a the participants in the experiment b the dosage of the drug c diastolic blood pressure d the experimental drug