An experiment was done to look at whether different relaxation techniques could predict sleep quality better than nothing. A sample of 400 participants were randomly allocated to one of four groups: massage, hot bath, reading, or nothing. For one month each participant received the same relaxation technique for 30 minutes before going to bed each night. A special device was attached to the participant's wrist that recorded their quality of sleep, providing them with a score out of 100. The outcome was the average quality-of-sleep score over the course of the month. Which of the following tables displays the most appropriate coding scheme for analysing these data? (Hint: We're interested in comparing those who have experienced a relaxation technique against those who didn't, so our baseline category will be 'nothing'.)