The president of a school club would like to purchase T-shirts for members of the club and asks members which size they would like to order. The results are shown in the histogram below. A histogram titled T-shirt sizes has size on the x-axis and frequency on the y-axis. Small, 15; medium, 22; large, 26; extra large, 5.

Which of the following is a true statement regarding the information shown in the histogram?

T-shirt size is a discrete quantitative variable.
T-shirt size is a continuous quantitative variable.
Frequency of each size is a discrete quantitative variable.
T-shirt size is a categorical variable.