The variable classified as categorical data or variable in this data set is the D. state bird.
A categorical variable is data that assumes a characteristic that cannot be quantified.
Categorical variables or data represent groups and quality. Categorical data assume two values: ordinal or nominal. They are ordinal if the data can be categorized, ordered, or ranked. The nominal data cannot be ranked but categorized.
Thus, area, population, and percent increase or decrease in population are not categorical variables, unlike state birds.
Learn more about categorical variables at https://brainly.com/question/14559783
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