A local bookstore is keeping a database of its customers to find out more about their spending habits and so that the store can start to make personal recommendations based on past purchases. The first $5$ lines of the database appear in the accompanying table.

$$a$)$ For each$$ variable, would you describe it as primarily$$ categorical, or$$ quantitative? If$$ quantitative, what are the$$ units? If$$ categorical, is it ordinal or simply$$ nominal?

$$b$)$ Are these data a time$$ series, or are these$$ cross$-$sectional? Explain briefly.

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Part $1$

$$a$)$ Describe the variable Transaction ID$.$ Choose the correct answer below.

A$.$

The variable Transaction ID is categorical and ordinal.

B$.$

The variable Transaction ID is categorical and$$ nominal, but could not be described as an identifier variable.

C$.$

The variable Transaction ID is categorical and$$ nominal, and could also be described as an identifier variable.

D$.$

The variable Transaction ID is$$ quantitative, with units counts.