An experiment looked at amount of weight lost in a year by subjects assigned to the Atkins diet. Tell whether each of the following focuses on data production, displaying and summarizing, probability, or statistical inference:

a. Researchers randomly assigned some patients to follow the Atkins diet.

b. Mean weight loss at one year was 2.1 kg.

c. If the subjects were a random sample taken from a population whose mean weight loss equaled zero, the probability of a sample mean weight loss as high as 2.1 kg is found to be 0.009.

d. Because the sample mean weight loss is significantly higher than zero, researchers concluded that the Atkins diet is effective.