A researcher is studying the relationship between sugar consumption and weight gain. Twelve volunteers were randomly assigned to one of two groups. The first group of five participants was put on a diet low in sugar and the second group of the remaining seven participants received 10% of their calories from sugar. After 8 weeks, weight gain was recorded from each participant. Which of the following basic principles of statistical design was not used in this experiment? a. Control
b. Randomization
c. Repetition
d. Blinding