A researcher is comparing the effectiveness of three devices designed to help people who snore. There are 120 people who snore participating in the experiment. Using a table of random digits, the researcher will randomly place the participants into three equally sized treatment groups suitable for comparison. Which design is the most appropriate for this experiment?

A Randomly number each person with 1, 2, or 3. Assign the people labeled 1 to the device 1 group, the people labeled 2 to the device 2 group, and the people labeled 3 to the device 3 group.
B Number each participant from 1 to 120. Reading numbers from left to right from a random number table, identify 80 unique numbers from 1 to 120. Assign the people whose labels are the first 40 numbers to the device 1 group. Assign the people whose labels are the second 40 numbers to the device 2 group. Assign the remaining people to the device 3 group.
C Number each participant from 000 to 119. Reading numbers from left to right on a random number table and looking at three digits at a time, identify 80 unique three-digit numbers from 000 to 119. Assign the people whose labels are the first 40 numbers to the device 1 group. Assign the people whose labels are the second 40 numbers to the device 2 group. Assign the remaining people to the device 3 group.
D Select a participant, and identify the first digit reading numbers from left to right on a random number table. If the first digit is a 1, 2, or 3, assign the participant to the device 1 group. If the first digit is a 4, 5, or 6, assign the participant to the device 2 group. If the first digit is a 7, 8, or 9, assign the participant to the device 3 group. If the first digit is a 0, skip that digit and move to the next one to assign the participant to a group. Repeat this process for each participant.