【单选题】Which of the following statements about pie charts is false?
A.
Pie charts are graphical representations of the relative frequency distribution.
B.
Pie charts are usually used to display the relative sizes of categories for numerical (quantitative) data.
C.
Pie charts always have the shape of a circle.
D.
The area of each slice of a pie chart is the proportion of the corresponding category of the frequency distribution of a nominal (categorical) variable.