An experiment investigates a dietary approach to treating depression. Researchers randomly assigned 20 subjects to two treatment groups, one taking a high dose of calcium supplements and the other a placebo. a) Why is it important to randomize in assigning the subjects to the two groups? O A. It should equalize the effects of unknown or uncontrollable sources of variation. O B. It eliminates the effects of unknown or uncontrollable sources of variation. O C. It assures that the experiment is controlled. O D. It makes conditions as similar as possible for all treatment groups. b) What would be the advantages and disadvantages of using 100 subjects instead of 20? O A. It would take more time and be more controlled but random assignment is more difficult with more subjects. O B. It assures that the subjects are randomly assigned but it would cause too much variability in the results. O C. It would maximize the impact of individual variability in the responses but it would be a more costly and time consuming experiment. O D. It would minimize the impact of individual variability in the responses but it would be a more costly and time consuming experiment. E