Which statement best describes an advantage of using the Subtotal dialog box? Only one function, Add, can be used to combine data quickly.
Data from multiple workbooks can be combined in a single step.
An option is available that can customize any function available in Excel.
Data can be summarized using a single step rather than by writing multiple formulas.

Data from multiple workbooks can be combined in a single step.

Explanation:

The Subtotal command allows the creation of groups automatically and common functions such as COUNT, SUM, and AVERAGE are used in the summarizing of data.

An advantage of using the Subtotal dialog box is that data from multiple workbooks can be combined in a single step. Therefore, the correct option is B.