A researcher designs an experiment to investigate whether soil bacteria trigger the synthesis of defense enzymes in plant roots. The design of the experiment is presented in Table 1. For each group in the experiment the researcher will determine the average rate of change in the amount of defense enzymes in the roots of the seedlings Table 1. An experiment to investigate the effect of soll bacteria on plant defenses Group Number of Seedings Type of Soil Treatment Solution 1 10 Sterlepotting sol Contains actively reproducing soll bacteria 2 10 Sterile potting sol Contains heille soll bacteria 3 10 Sterle porting soil Contains no bacteria Which of the following statements best helps justify the inclusion of group 2 as one of the controls in the experiment? A) I will show whether the changes observed in group 1 depend on the metabolic activity of Boll bacteria B) will show whether the changes observed in group 1 depend on the type of plants used in the experiment. C) It will show the average growth rate of seedings that are maintained in a nonsterile environment D) I will show the changes that occur in the roots of seedlings following an infection by soll bacteria.