A physician is testing the effectiveness of two new exercise plans on 70 subjects. To assign the subjects to the two treatment groups, he writes "Plan 1” on one slip of paper and "Plan 2” on another slip of paper. He randomly picks one of the slips, and assigns the first 35 subjects who signed up to that plan, and assigns the last 35 subjects to the other plan. Select the statement that best describes the composition of the treatment groups. Group of answer choices