What statistical tool is used to show how two categorical variables correlate?

The correct answer is cross tabulation, which is a statistical tool specifically designed to analyze the relationship between two categorical variables. It organizes data into a matrix format, allowing an easy comparison of the frequencies or counts of observations that fall into two categories. By displaying the joint distribution of the variables, cross tabulation helps in identifying patterns, such as how one variable may be related to another. This is particularly useful in social sciences, marketing research, and survey analysis where categorical data is common.

In contrast, while a histogram represents the distribution of a single categorical variable, a box plot is used to display the distribution of numerical data and highlight medians and quartiles. A scatter plot is employed primarily to examine relationships between two continuous variables rather than categorical variables. Each of these tools serves a different purpose and is suitable for different types of data analysis, making cross tabulation the appropriate choice for analyzing the correlation between two categorical variables.