Which tool would you use to turn rows into columns?

The tool that is used to turn rows into columns is the Cross Tab tool. This tool allows users to pivot data in such a way that it transforms unique values from a specified column into new column headers. As a result, it effectively reorganizes data for better analysis and visual representation.

When using the Cross Tab tool, you specify the data you want to aggregate and the field whose unique values will become the new columns. The intersection of these new columns and the aggregated values allows for a clearer comparison of the data.

In contrast, other tools serve different functions. The Append Fields tool is designed to add fields from one dataset to another dataset, without changing the structure of how the data is arranged. The Union tool stacks rows from different datasets on top of each other, combining them vertically rather than transforming them into columns. The Transpose tool flips the orientation of the data, swapping rows and columns, but does not create new column headers from unique values in the way that the Cross Tab tool does.

Thus, the Cross Tab tool is specifically designed for the purpose of transforming rows into columns, making it the correct choice for this question.