Maintaining adequate calcium intake reduces the rate of
a. vitamin a synthesis
b. age-related bone loss
c. age-related vision loss
d. hypervitaminosis

How is the central idea developed further? (a) the author elaborates on the treatments for allergies in adults and how they work. (b) the author quotes the reactions of experts and the methods used to conduct the study. (c) the author compares the different rates of food allergies shown in children and adults. (d) the author indicates the limitations of the study because of differences in health care.