What feature would a System Administrator use to restrict what users can see?

The correct choice, Filters, plays a crucial role in how data is displayed and controlled for end users in Smartsheet. Filters allow a System Administrator to specify what rows of data can be viewed by users based on certain criteria. By applying filters, you can ensure that users only see information that is relevant to them, enhancing data security and user experience. This is particularly useful in scenarios where sensitive information may exist within a sheet that should not be accessible to all users.

In contrast, Reports are designed to aggregate and present data from multiple sheets but do not inherently restrict what users can access within the source sheets. Dashboards compile various visualizations and data displays but again do not control visibility directly on a per-user basis. Formulas are powerful tools for calculations and data manipulation within individual sheets but do not affect the visibility and access levels of that data for different users. Therefore, Filters are indeed the most effective feature for restricting what users can see in a Smartsheet environment.