An experiment is conducted in order to determine if Vitamin D can reduce the number of asthma attacks in children who suffer from asthma.A total of 200 children between the ages of 6- and 16-years volunteer, with the consent of their parents, to take part in this study.All of these children had suffered at least one asthma attack in the past year.Half of the children are randomly assigned to take a particular dosage of Vitamin D each day, and the other half are randomly assigned to take a sugar pill each day.After one year, researchers find that compared to the sugar pill, children who took Vitamin D on a daily basis did not experience any reduction in the number of asthma attacks.Based on what you know about this study, what should we conclude?

A.Because the sample was composed of volunteers, the researchers had no way of controlling for possible lurking variables.

B.Age of the child should be considered a lurking variable.

C.Because random assignment was used in the study, it is okay to generalize the findings from this study to a larger population.

D.There was no placebo used in this study.

E.None of the above statements are appropriate conclusions to make about this study.