Which of the following could be an assumption on which the researchers relied in drawing their conclusion? A. Babies over 9 months are less likely to be obese than are babies under 9 months because babies over 9 months eat less frequently than do babies under 9 months. B. In the months before the study, the feeding practices of the mothers in the study did not differ significantly from their feeding practices at the time of the study. C. Babies gain weight at a slower rate between the ages of 7 and 9 months than they do between the ages of 4 and 6 months. D. Obesity is genetically rather than environmentally determined. Breast-fed babies are more likely to be obese than are formula-fed babies. E. Breast-fed babies are more likely to be obese than are formula-fed babies.