Which step is necessary to filter query results using AutoFilter?

To filter query results using AutoFilter, the necessary step is to select the 'Select All' checkbox to reset the current filter settings. This action allows users to begin with a fresh filter setup before specifying new criteria. By resetting to the default, you ensure that any previously applied filters are cleared, enabling you to see all available data and efficiently apply new conditions as needed.

The other options do not accurately reflect the necessary steps for filtering with AutoFilter. For instance, clicking 'OK' is not a prerequisite for applying filters; rather, it’s typically used to confirm settings after adjustments have been made. Opening the query in Datasheet view is a common practice for viewing data, but it is not strictly required to initiate filtering. Additionally, pressing F12 does not activate filtering; specific shortcut keys or commands are designated for that purpose, depending on the software being used.