Which of the Following Statements Is True

Which of the following statements is true? $\begin{array}{|l|l|}\hline A&\text {A histogram is created by drawing rectangles whose bases correspond to the class intervals, }\\&\text {and the area of each rectangle equals the total }\\&\text { number of observations in the sample.}\\\hline B&\text { A histogram can be used for only categorical variables.}\\\hline C&\text { A histogram is created by drawing rectangles whose bases correspond to the number }\\&\text { of observations in each class.}\\\hline D&\text { A histogram is created by drawing rectangles whose bases correspond to the class intervals, and the area}\\&\text { of each rectangle equals the number of observations in that class.}\\\hline \end{array}$