Which of the following options cannot be set as the On Click Destination for a Button in a Screen?

In the context of OutSystems, a Button's On Click Destination determines the action that will occur when the button is clicked. This destination can be set to various types, but there are specific constraints regarding what can be assigned.

Setting a Button's On Click Destination to a Screen allows navigation within the application, enabling users to transition to another screen directly when the button is clicked. Similarly, setting it to a Client Action executes a specific piece of logic, such as validating inputs or updating data, thereby enhancing interactivity.

Assigning a Button's destination to an External Site is also feasible. This option allows the application to redirect users to a different URL outside of the application's context, which is often used for linking to third-party websites or resources.

In contrast, Blocks are not designed to be interactive targets for navigation or action. A Block typically represents a reusable piece of user interface that can contain other UI elements and logic but does not function independently as a destination for user interactions like a Button's On Click event. This is why a Block cannot be set as the On Click Destination for a Button in a Screen, as it lacks the structural capability to handle navigation or execution of actions in the way that Screens, Client Actions, and External Sites can.