Which element allows users to select one or more options from a set?

The element that allows users to select one or more options from a set is the checkbox. Checkboxes are specifically designed for multi-select scenarios, where users can choose multiple items from a list of available options. Each checkbox operates independently, enabling users to check or uncheck any combination of choices as desired.

In contrast, other options like a dropdown menu typically only allow for single selections unless it’s designed to permit multiple selections, but that’s less common. A text input is used for user input of text but does not facilitate the selection of predefined options, and a submit button is utilized to send the selected data but does not allow for option selection itself. Thus, the checkbox is the correct choice for enabling users to make multiple selections conveniently.