A weight-loss diet claims that it causes weight loss by eliminating carbohydrates (breads and starches) from the diet. To test this claim, researchers randomly assign overweight subjects to two groups. Both groups eat the same amount of calories, but one group eats almost no carbs, and the other group includes carbs in their meals. After 2 months, the researchers test the claim that the no-carb diet is better than the usual diet. They record the proportion of each group that lost more than 5% of their initial weight. They then announce that they failed to reject the null hypothesis. Which of the following are valid interpretations of the researchers’ findings?

a. There were no significant differences in effectiveness between the no-carb diet and the carb diet.

b. The no-carb diet and the carb diet were equally effective.

c. The researchers did not see enough evidence to conclude that the no-carb diet was more effective.

d. The no-carb diet was less effective than the carb diet.