To create a drop-down list using data validation, which option must be selected in the Data Validation dialog?

To create a drop-down list using data validation in a program like Excel, it is essential to select 'List' from the Allow drop-down menu in the Data Validation dialog. This option specifically enables the creation of a drop-down list, allowing users to choose from predefined options.

When 'List' is selected, you can then specify the source of the list items, which could be a range of cells containing the various choices or can be entered directly into the dialog. This functionality enhances data entry accuracy and consistency because it restricts entries to the specified list, helping to prevent errors that may arise from manual input.

The other options, such as choosing 'Text Length', 'Decimal', or 'Date', serve different purposes and do not create a drop-down list. 'Text Length' would apply constraints based on the number of characters; 'Decimal' would restrict the input to decimal numbers; and 'Date' would limit entries to date formats. These choices help manage input data in different ways but do not facilitate a drop-down selection like the 'List' option does.