When connecting Power Query Editor to a database, which transformation will ensure that new columns are not displayed during a scheduled refresh?

The choice that involves using the Select Columns command and choosing the specific columns to keep is the most effective transformation to ensure that new columns do not appear during a scheduled refresh. When you explicitly select which columns to include in your data model, Power BI is directed to ignore any columns that are not explicitly defined in this selection.

This method provides control over the dataset used in your reports and dashboards, ensuring that only the desired columns are brought into Power BI. It protects against potential changes in the underlying database schema, such as the addition of new columns, which could disrupt the reporting data structure or create confusion for users.

In contrast, other options would either remove necessary columns or might retain columns not explicitly filtered out. For example, removing other columns or filtering rows does not guarantee that unwanted extra columns will not come through in a refresh, as the query could still include additional columns not accounted for in the transformations.