Which function is used to create a total row that sums the costs in a table?

The function used to create a total row that sums the costs in a table is the SUM function. This function is specifically designed to add together a range of numeric values, making it ideal for calculating totals, such as costs in a financial context. When you apply the SUM function to the specified range of cells in a table, it efficiently calculates the total by summing all the values within that range.

In the context of the question, while the other functions mentioned—such as AVERAGE, SAVE, and TOTAL—serve different purposes, they do not directly achieve the task of summing values within a table. AVERAGE calculates the mean of a set of numbers, SAVE is not a function related to calculations, and TOTAL is not a standard function in spreadsheet applications like SUM. Therefore, using the SUM function is the most appropriate choice for creating a total row to sum costs.